Immuno-based retargeted endopeptidase activity assays

ABSTRACT

The present specification discloses a retargeted endopeptidase pharmaceutical wherein the activity has been determined by the methods disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation and claims priority pursuant to 35U.S.C. §120 to U.S. patent application Ser. No. 13/801,711, filed Mar.13, 2013, which is a continuation of U.S. patent application Ser. No.12/723,595, filed Mar. 12, 2010, which is now U.S. Pat. No. 8,455,203,which claims priority pursuant to 35 U.S.C. §119(e) to U.S. ProvisionalPatent Application Ser. No. 61/160,217 filed Mar. 13, 2009, each ofwhich is incorporated entirely by reference.

The sequences disclosed in the present specification are contained inthe Sequence Listing submitted with the present specification which ishereby incorporated by reference in its entirety.

The ability of Clostridial toxins, such as, e.g., Botulinum neurotoxins(BoNTs), BoNT/A, BoNT/B, BoNT/C1, BoNT/D, BoNT/E, BoNT/F and BoNT/G, andTetanus neurotoxin (TeNT), to inhibit neuronal transmission are beingexploited in a wide variety of therapeutic and cosmetic applications,see e.g., William J. Lipham, Cosmetic and Clinical Applications ofBotulinum Toxin (Slack, Inc., 2004). Clostridial toxins commerciallyavailable as pharmaceutical compositions include, BoNT/A preparations,such as, e.g., BOTOX® (Allergan, Inc., Irvine, Calif.),DYSPORT®/RELOXIN®, (Ipsen Ltd., Slough, England), PURTOX® (Mentor Corp.,Santa Barbara, Calif.), XEOMIN® (Merz Pharmaceuticals, GmbH., Frankfurt,Germany), NEURONOX® (Medy-Tox, Inc., Ochang-myeon, South Korea), BTX-A(Biogen-tech Ltd., University, Yantai, Shandong, China); and BoNT/Bpreparations, such as, e.g., MYOBLOC®/NEUROBLOC® (SolsticeNeurosciences, Inc., South San Francisco, Calif.). As an example, BOTOX®is currently approved in one or more countries for the followingindications: achalasia, adult spasticity, anal fissure, back pain,blepharospasm, bruxism, cervical dystonia, essential tremor, glabellarlines or hyperkinetic facial lines, headache, hemifacial spasm,hyperactivity of bladder, hyperhidrosis, juvenile cerebral palsy,multiple sclerosis, myoclonic disorders, nasal labial lines, spasmodicdysphonia, strabismus and VII nerve disorder.

A Clostridial toxin treatment inhibits neurotransmitters andneuropeptide release by disrupting the exocytotic process used tosecrete the neurotransmitters and neuropeptides into the synaptic cleft.There is a great desire by the pharmaceutical industry to expand the useof Clostridial toxin therapies beyond its current myo-relaxantapplications to treat sensory nerve-based ailment, such as, e.g.,various kinds of chronic pain, neurogenic inflammation and urogenitaldisorders, as well as other disorders, such as, e.g., pancreatitis. Oneapproach that is currently being exploited to expand Clostridialtoxin-based therapies involves modifying a Clostridial toxin so that themodified toxin has an altered cell targeting capability for a neuronalor non-nuronal cell of interest. Called either re-targeted endopeptidaseor Targeted Vesicular Exocytosis Modulator Proteins (TVEMPs), thesemolecules achieve their exocytosis inhibitory effects by using a targetreceptor present on the neuronal or non-neuronal target cell ofinterest. This re-targeted capability is achieved by replacing anaturally-occurring binding domain of a Clostridial toxin with atargeting domain showing a selective binding activity for anon-Clostridial toxin receptor present in a neuronal or non-neuronaltarget cell of interest. Such modifications to a binding domain resultin a molecule that is able to selectively bind to a non-Clostridialtoxin receptor present on the target cell. A re-targeted endopeptidasecan bind to a target receptor, translocate into the cytoplasm, and exertits proteolytic effect on the SNARE complex of the neuronal ornon-neuronal target cell of interest.

One group of re-targeted endopeptidase comprises molecules having anopioid targeting domain. These opioid re-targeted endopeptidasescomprise an opioid targeting domain, a Clostridial toxin translocationdomain, and a Clostridial toxin enzymatic domain. Non-limiting examplesof opioid re-targeted endopeptidase, or opioid-TVEMPs, are described in,e.g., Keith A. Foster et al., Clostridial Toxin Derivatives Able ToModify Peripheral Sensory Afferent Functions, U.S. Pat. No. 5,989,545;J. Oliver Dolly et al., Activatable Recombinant Neurotoxins, U.S. Pat.No. 7,132,259; Stephan Donovan, Clostridial Toxin Derivatives andMethods For Treating Pain, U.S. Pat. No. 7,244,437; Stephan Donovan,Clostridial Toxin Derivatives and Methods For Treating Pain, U.S. Pat.No. 7,413,742; Stephan Donovan, Clostridial Toxin Derivatives andMethods For Treating Pain, U.S. Pat. No. 7,415,338; Lance E. Steward etal., Multivalent Clostridial Toxin Derivatives and Methods of Their Use,U.S. Pat. No. 7,514,088; Keith A. Foster, Fusion Proteins, U.S. PatentPublication 2008/0064092; Keith A. Foster, Fusion Proteins, U.S. PatentPublication 2009/0035822; Lance E. Steward et al., MultivalentClostridial Toxin Derivatives and Methods of Their Use, U.S. PatentPublication 2009/0048431; Keith A. Foster, Non-Cytotoxic ProteinConjugates, U.S. Patent Publication 2009/0162341; Keith A. Foster etal., Re-targeted Toxin Conjugates, International Patent Publication WO2005/023309; and Lance E. Steward, Modified Clostridial Toxins withEnhanced Translocation Capabilities and Altered Targeting Capabilitiesfor Non-Clostridial Toxin Target Cells, International Patent ApplicationWO 2008/008805; each of which is hereby incorporated by reference in itsentirety.

One general difference between re-targeted endopeptidases andClostridial toxins is that because re-targeted endopeptidases typicallydo not target motor neurons, the lethality associated with over-dosing amammal with a re-targeted endopeptidase is greatly minimized, if notavoided altogether. For example, opioid re-targeted endopeptidases canbe administered at 10,000 times the therapeutically effective dosebefore evidence of lethality is observed, and this lethality is due tothe passive diffusion of the molecule and not via the intoxicationprocess. Thus, for all practical purposes re-targeted endopeptidases arenon-lethal molecules. Although this non-lethal property is of greattherapeutic benefit, a manufacturing problem arises because the standardactivity assay used to manufacture Clostridial toxin-based biologics isa mouse LD₅₀ bioassay, a lethality test. S. S. Arnon et al., JAMA 285:1059-1070 (2001). Currently a mouse LD₅₀ bioassay is used by allpharmaceutical manufacturers to express the potency of their Clostridialtoxin preparations. In fact, the activity units for Clostridial toxinsare mouse LD₅₀ units. However, because re-targeted endopeptidases areessentially non-lethal, a mouse LD₅₀ bioassay cannot be used to assessthe potency of these molecules. Thus, a simple, reliable, validated, andgovernmental agency acceptable activity assay that can evaluate theintegrity of all the steps necessary in re-targeted endopeptidase uptakewould be of significant value.

The present specification provides novel compositions, cells, andmethods for assaying the activity of re-targeted endopeptidases usefulfor various industries, such as, e.g., the pharmaceutical and foodindustries, and provides related advantages as well. Such compositions,cells, and methods do not use live animals or tissues taken from liveanimals, but can evaluate all the steps necessary for re-targetedendopeptidase action.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show a schematic of the current paradigm ofneurotransmitter release and Clostridial toxin intoxication in a centraland peripheral neuron. FIG. 1A shows a schematic for theneurotransmitter release mechanism of a central and peripheral neuron.The release process can be described as comprising two steps: 1) vesicledocking, where the vesicle-bound SNARE protein of a vesicle containingneurotransmitter molecules associates with the membrane-bound SNAREproteins located at the plasma membrane; and 2) neurotransmitterrelease, where the vesicle fuses with the plasma membrane and theneurotransmitter molecules are exocytosed. FIG. 1B shows a schematic ofthe intoxication mechanism for tetanus and botulinum toxin activity in acentral and peripheral neuron. This intoxication process can bedescribed as comprising four steps: 1) receptor binding, whereClostridial toxin binds to a Clostridial receptor complex and initiatesthe intoxication process; 2) complex internalization, where after toxinbinding, a vesicle containing a toxin/receptor system complex isendocytosed into the cell; 3) light chain translocation, where multipleevents are thought to occur, including changes in the internal pH of thevesicle, formation of a channel pore comprising the H_(N) domain ofClostridial toxin heavy chain, separation of the Clostridial toxin lightchain from the heavy chain, and release of the light chain and 4)enzymatic target modification, where the light chain of Clostridialtoxin proteolytically cleaves its target SNARE substrates, such as,e.g., SNAP-25, VAMP or Syntaxin, thereby preventing vesicle docking andneurotransmitter release.

FIG. 2 shows a full dose response to the re-targeted endopeptidase Noc/Ain the ORL-1 Clone #6 clonal cell line overexpressing ORL-1. Specificuptake of Noc/A can be observed in the ORL-1Clone #6 clonal cell lineoverexpressing ORL-1. The treatment with Noc/A (LHN/A plus bindingligand nociceptin variant) and LH_(N)/A (LC/A and H_(N) without anybinding domain) performed on ORL-1 stable cell line clone #6 in the ECLELISA for cleaved SNAP-25₁₉₇ demonstrated that uptake of Noc/A isspecific in this clonal cell line. The clonal cell line also show greatsensitivity for Noc/A with an EC₅₀ of 1.2 nM.

FIG. 3 shows a full dose response to Noc/A in the SK-N-DZ single-cellderived clones #3 and #22. Specific uptake of Noc/A on SK-N-DZ clones #3and #22 when compared to LH_(N)/A (n=4 independent experiments run).Cells were plated on poly-D-lysine 96-well plates in RPMISFM+N2+B27+NGF. Treatment with compounds was for 22 hours. ECL ELISA forcleaved SNAP-25₁₉₇ demonstrated that uptake of Noc/A is specific in thisclonal cell lines. The clonal cell lines also show great sensitivity forNoc/A with an EC₅₀ of 0.3 nM for clone #3 and an EC₅₀ of 0.9 nM forclone #22.

FIG. 4 shows an ECL sandwich ELISA assay results from ORL1 ND7 clones1C11, 4B7, and 4C9 treated with re-targeted endopeptidase Noc/A.Parental ND7 and ORL1 ND7 clones were treated for 24 hours with Noc/Afollowed by two days of incubation. Parental ND7 EC₅₀ could not becalculated since it only reached approximately 50% SNAP-25₁₉₇ cleavage.Clones 4B7 and 1C11 reach more than 80% SNAP-25₁₉₇ cleavage. EC₅₀ valueswere calculated to be 5.7±0.5, 6.7±1, and 8.6±2 nM respectively.

FIG. 5 shows an anti-nociceptin polyclonal antibodies can blockre-targeted endopeptidase Noc/A uptake in SK-N-DZ clone #3, clone #22,and AGN P33 ORL-1 clone #6 cell lines. Cells were plated onpoly-D-lysine 96-well plates in RPMI SFM+N2+B27+NGF and treated for 22hours in serum-free media containing with the Anti-nociceptin polyclonalantibodies at different dilutions (0-3 μg/mL) in 1 nM Noc/A.

FIG. 6 shows cells from SiMa clone AF4 and the established cell linePC-12 were treated with the re-targeted endopeptidase Dyn/A atconcentrations from 0.017 nM to 1 μM as depicted in the Western blotimage. Dose-dependent uptake could be observed for both cell lines.

FIGS. 7A and 7B show normalized BIAcore SPR curves of 7.8 nM of theantibodies 2E2A6, 1D3B8, 3C1A5 and 2C9B10 and commercial MC-6050 andMC-6053. FIG. 7A shows the normalized data for the on-rate of eachantibody. FIG. 7B shows the normalized data for the off-rate of eachantibody.

DETAILED DESCRIPTION

The present specification provides novel assays for determining thepresence or absence of an active retargeted endopeptidase in a sampleand for determining the activity/potency of a re-targeted endopeptidase.The novel cell-based assays disclosed in the present specification relyon cells, reagents and detection methods that enable the assay to detectnanomolar quantities of a re-targeted endopeptidase in a sample. Thecell-based assays disclosed in the present specification serve toanalyze multiple functions a re-targeted endopeptidase, namely,re-targeted endopeptidase binding to a cell surface receptor,internalization of the endopeptidase-receptor complex, enzymatic domaintranslocation into the cytoplasm, enzymatic domain cleavage ofsubstrate. As discussed further below, the novel methods andcompositions can be used to analyze crude and bulk samples as well ashighly purified di-chain re-targeted endopeptidases and formulatedre-targeted endopeptidase products and further are amenable to automatedhigh throughput assay formats.

Thus, one aspect disclosed in the present specification provides immuneresponse inducing compositions for producing α-SNAP-25 antibodies thatcan selectively bind to an epitope comprising a SNAP-25 cleavage producthaving a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond. Immune response inducing compositions can comprise anadjuvant and an immune response inducing composition including a SNAP-25antigen, a carrier linked to a SNAP-25 antigen, or a carrier linked to aflexible spacer linked to a SNAP-25 antigen, where the flexible linkerintervenes between the SNAP-25 antigen and the carrier. It is envisionedthat any and all SNAP-25 antigens that triggers an immune response thatproduce a α-SNAP-25 antibody that can selectively bind to a SNAP-25epitope having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond can be useful as a SNAP-25 antigen,including, without limitation, a SNAP-25 antigen derived from anaturally occurring SNAP-25, a SNAP-25 antigen derived from anon-naturally occurring SNAP-25, and a SNAP-25 antigen comprising animmunoreactive fragment of the SNAP-25, the SNAP-25 from a naturallyoccurring SNAP-25 or a non-naturally occurring SNAP-25. SNAP-25 antigensuseful for producing α-SNAP-25 antibodies that can selectively bind to aSNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond include, without limitation, SNAP-25antigens comprising a SNAP-25 peptide having a carboxylated C-terminalglutamine linked to a carrier peptide, including, without limitation SEQID NO:38. Other Immune response inducing compositions useful for makingα-SNAP-25 antibodies that can selectively bind to a SNAP-25 epitopehaving a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond include, without limitation, an immune response inducingcomposition comprising a carrier linked to a flexible linker linked to aSNAP-25 antigen a carboxylated C-terminal glutamine, wherein theflexible linker intervenes between the SNAP-25 antigen and the carrier.It is envisioned that any and all adjuvants can be useful in such animmune response inducing composition, including, without limitation,polyethylene glycol (PEG), monomethoxypolyethylene glycol (mPEG),polyvinyl alcohol (PVA), complete and incomplete Freund's adjuvant.

Another aspect disclosed in the present specification provides methodsof producing an α-SNAP-25 antibody that can selectively bind to anepitope comprising a SNAP-25 cleavage product having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond. Aspects ofthis method comprise the steps of (a) administering to an animal aSNAP-25 immune response inducing composition disclosed in the presentspecification; (b) collecting from the animal a sample containing anα-SNAP-25 antibody or α-SNAP-25 antibody-producing cell; and (c)isolating the α-SNAP-25 antibody from the sample. The methods disclosedare useful for making either α-SNAP-25 monoclonal antibodies that canselectively bind to an epitope comprising a SNAP-25 cleavage producthaving a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond or α-SNAP-25 polyclonal antibodies that can selectivelybind to an epitope comprising a SNAP-25 cleavage product having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond.

Still another aspect disclosed in the present specification providesα-SNAP-25 antibodies that selectively bind to an epitope comprising aSNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond. Such α-SNAP-25 antibodies include bothnaturally-occurring and non-naturally-occurring antibodies, as well as,monoclonal α-SNAP-25 antibodies or polyclonal α-SNAP-25 antibodies.Monoclonal α-SNAP-25 antibodies useful as α-SNAP-25 antibodies thatselectively bind to a SNAP-25 antigen having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond, include, withoutlimitation, the monoclonal α-SNAP-25 antibodies produced from hybridomacell lines 1D3B8, 2C9B10, 2E2A6, 3C1A5 and 3C3E2.

Yet another aspect disclosed in the present specification providesimmuno-based methods of detecting re-targeted endopeptidase activity.Aspects of this method comprise the steps of (a) treating a cell from anestablished cell line with a sample comprising a re-targetedendopeptidase, wherein the cell from an established cell line issusceptible to re-targeted endopeptidase activity by the re-targetedendopeptidase; (b) isolating from the treated cell a SNAP-25 componentcomprising a SNAP-25 cleavage product having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond; (c) contacting theSNAP-25 component with an α-SNAP-25 antibody disclosed in the presentspecification; and (d) detecting the presence of an antibody-antigencomplex comprising the α-SNAP-25 antibody and the SNAP-25 cleavageproduct having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond; wherein detection by the antibody-antigencomplex is indicative of re-targeted endopeptidase activity. Theα-SNAP-25 antibody of step (c) can optionally be linked to a solid phasesupport.

Yet another aspect disclosed in the present specification providesimmuno-based methods of detecting opioid-TVEMP activity. Aspects of thismethod comprise the steps of (a) treating a cell from an establishedcell line with a sample comprising a re-targeted endopeptidase, whereinthe cell from an established cell line can uptake a re-targetedendopeptidase; (b) isolating from the treated cell a SNAP-25 componentcomprising a SNAP-25 having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond; (c) contacting the SNAP-25 componentwith an α-SNAP-25 antibody disclosed in the present specification; and(d) detecting the presence of an antibody-antigen complex comprising theα-SNAP-25 antibody and the SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond; wherein detection bythe antibody-antigen complex is indicative of re-targeted endopeptidaseactivity. The α-SNAP-25 antibody of step (c) can optionally be linked toa solid phase support.

A further aspect disclosed in the present specification provides methodsof determining re-targeted endopeptidase immunoresistance in a mammal.Aspects of this method comprise the steps of (a) adding a re-targetedendopeptidase to a test sample obtained from a mammal being tested forthe presence or absence of α-re-targeted endopeptidase neutralizingantibodies; (b) treating a cell from an established cell line with thetest sample, wherein the cell from an established cell line issusceptible to re-targeted endopeptidase activity; (c) isolating fromthe treated cells a SNAP-25 component comprising a SNAP-25 cleavageproduct having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond; (d) contacting the SNAP-25 component withan α-SNAP-25 antibody disclosed in the present specification; (e)detecting the presence of an antibody-antigen complex comprising theα-SNAP-25 antibody and the SNAP-25 cleavage product having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond; (f) repeating steps a-e with a negative control sample instead ofa test sample; and (g) comparing the amount of antibody-antigen complexdetected in step (e) to the amount of antibody-antigen complex detectedin step (f), wherein detection of a lower amount of antibody-antigencomplex detected in step (e) relative to the amount of antibody-antigencomplex detected in step (f) is indicative of the presence ofα-re-targeted endopeptidase neutralizing antibodies. The α-SNAP-25antibody of step (d) can optionally be linked to a solid phase support.The control sample in step (f) can also include a positive controlsample, in addition to the negative control sample.

Clostridia toxins produced by Clostridium botulinum, Clostridium tetani,Clostridium baratii and Clostridium butyricum are the most widely usedin therapeutic and cosmetic treatments of humans and other mammals.Strains of C. botulinum produce seven antigenically-distinct serotypesof botulinum toxins (BoNTs), which have been identified by investigatingbotulism outbreaks in man (BoNT/A, BoNT/B, BoNT/E and BoNT/F), animals(BoNT/C1 and BoNT/D), or isolated from soil (BoNT/G). While all sevenbotulinum toxin serotypes have similar structure and biologicalproperties, each also displays heterogeneous characteristics, such as,e.g., different pharmacological properties. In contrast, tetanus toxin(TeNT) is produced by a uniform group of C. tetani. Two other species ofClostridia, C. baratii and C. butyricum, also produce toxins similar toBoNT/F and BoNT/E, respectively.

Clostridial toxins are each translated as a single chain polypeptide ofapproximately 150 kDa that is subsequently cleaved by proteolyticscission within a disulfide loop by a naturally-occurring protease, suchas, e.g., an endogenous Clostridial toxin protease or anaturally-occurring protease produced in the environment. Thisposttranslational processing yields a di-chain molecule comprising anapproximately 50 kDa light chain (LC) and an approximately 100 kDa heavychain (HC) held together by a single disulfide bond and noncovalentinteractions. Each mature di-chain molecule comprises three functionallydistinct domains: 1) an enzymatic domain located in the LC that includesa metalloprotease region containing a zinc-dependent endopeptidaseactivity which specifically targets core components of theneurotransmitter release apparatus; 2) a translocation domain containedwithin the amino-terminal half of the HC (H_(N)) that facilitatesrelease of the LC from intracellular vesicles into the cytoplasm of thetarget cell; and 3) a binding domain found within the carboxyl-terminalhalf of the HC (H_(C)) that determines the binding activity and bindingspecificity of the toxin to the receptor complex located at the surfaceof the target cell.

The binding, translocation and enzymatic activity of these threefunctional domains are all necessary for toxicity. While all details ofthis process are not yet precisely known, the overall cellularintoxication mechanism whereby Clostridial toxins enter a neuron andinhibit neurotransmitter release is similar, regardless of serotype orsubtype. Although the applicants have no wish to be limited by thefollowing description, the intoxication mechanism can be described ascomprising at least four steps: 1) receptor binding, 2) complexinternalization, 3) light chain translocation, and 4) enzymatic targetmodification (FIG. 1). The process is initiated when the HC domain of aClostridial toxin binds to a toxin-specific receptor system located onthe plasma membrane surface of a target cell. The binding specificity ofa receptor complex is thought to be achieved, in part, by specificcombinations of gangliosides and protein receptors that appear todistinctly comprise each Clostridial toxin receptor complex. Once bound,the toxin/receptor complexes are internalized by endocytosis and theinternalized vesicles are sorted to specific intracellular routes. Thetranslocation step appears to be triggered by the acidification of thevesicle compartment. This process seems to initiate importantpH-dependent structural rearrangements that increase hydrophobicity,promote pore formation, and facilitate separation of the heavy and lightchains of the toxin. Once separated, the light chain endopeptidase ofthe toxin is released from the intracellular vesicle into the cytosolwhere it appears to specifically target core components of theneurotransmitter release apparatus. These core proteins,vesicle-associated membrane protein (VAMP)/synaptobrevin,synaptosomal-associated protein of 25 kDa (SNAP-25) and Syntaxin, arenecessary for synaptic vesicle docking and fusion at the nerve terminaland constitute members of the soluble N-ethylmaleimide-sensitivefactor-attachment protein-receptor (SNARE) family. BoNT/A and BoNT/Ecleave SNAP-25 in the carboxyl terminal region, releasing a nine ortwenty six amino acid fragment, respectively, and BoNT/C1 also cleavesSNAP-25 near the carboxyl terminus releasing an eight amino acidfragment. The botulinum serotypes BoNT/B, BoNT/D, BoNT/F and BoNT/G, andtetanus toxin, act on the conserved central portion of VAMP, and releasethe amino terminal portion of VAMP into the cytosol. BoNT/C1 cleavessyntaxin at a single site near the cytosolic membrane surface. Theselective proteolysis of synaptic SNAREs accounts for the block ofneurotransmitter release caused by Clostridial toxins in vivo. The SNAREprotein targets of Clostridial toxins are common to exocytosis in avariety of non-neuronal types; in these cells, as in neurons, lightchain peptidase activity inhibits exocytosis, see, e.g., Yann Humeau etal., How Botulinum and Tetanus Neurotoxins Block NeurotransmitterRelease, 82 (5) Biochimie. 427-446 (2000); Kathryn Turton et al.,Botulinum and Tetanus Neurotoxins: Structure, Function and TherapeuticUtility, 27 (11) Trends Biochem. Sci. 552-558. (2002); Giovanna Lalli etal., The Journey of Tetanus and Botulinum Neurotoxins in Neurons, 11 (9)Trends Microbiol. 431-437, (2003).

Re-targeted endopeptidases generally substitute the naturally-occurringdi-chain loop protease cleavage site with an exogenous protease cleavagesite. See e.g., Dolly, J. O. et al., Activatable Clostridial Toxins,U.S. Pat. No. 7,419,676, which is hereby incorporated by reference.Although re-targeted endopeptidases vary in their overall molecularweight because of the size of the targeting moiety, the activationprocess and its reliance on cleavage at the exogenous cleavage site toproduce a di-chain molecule is essentially the same as that forClostridial toxins. See e.g., Steward, L. E. et al., ActivatableClostridial Toxins, U.S. Patent Publication 2009/0005313; Steward, L. E.et al., Modified Clostridial Toxins with Enhanced TranslocationCapabilities and Altered Targeting Activity For Non-Clostridial ToxinTarget Cells, U.S. patent application Ser. No. 11/776,075; Steward, L.E. et al., Modified Clostridial Toxins with Enhanced TranslocationCapabilities and Altered Targeting Activity for Clostridial Toxin TargetCells, U.S. Patent Publication 2008/0241881, each of which is herebyincorporated by reference.

Aspects of the present disclosure comprise, in part, an immune responseinducing composition for producing α-SNAP-25 antibodies that canselectively bind to a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond. As used herein, theterm “immune response inducing composition” refers to a compositioncomprising a SNAP-25 antigen which, when administered to an animal,stimulates an immune response against the SNAP-25 antigen, therebyproducing α-SNAP-25 antibodies that can selectively bind to a SNAP-25having a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond. The term “immune response” refers to any response by theimmune system of an animal to an immune response inducing composition.Exemplary immune responses include, but are not limited to, cellular aswell as local and systemic humoral immunity, such as, e.g., CTLresponses, including antigen-specific induction of CD8+ CTLs, helperT-cell responses, including T-cell proliferative responses and cytokinerelease, and B-cell responses including, e.g., an antibody producingresponse. The term “inducing an immune response” refers toadministration of an immune response inducing composition or apolynucleotide encoding the immune response inducing composition, wherean immune response is affected, i.e., stimulated, initiated or induced.

An SNAP-25 immune response inducing composition comprises a SNAP-25antigen. As used herein, the term “antigen” refers to a molecule thatelicits an immune response and includes, without limitation, peptides,polysaccharides and conjugates of lipids, such as, e.g., lipoproteinsand glycolipids. As used herein, the term “SNAP-25 antigen” refers toany antigen which has a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond that can elicit an immune response. ASNAP-25 antigen used in an immune response inducing composition must belarge enough to be substantially unique in sequence, thus reducing thepossibility of producing antibodies that are cross reactive againstantigens other than SNAP-25. In addition, a SNAP-25 antigen used in animmune response inducing composition must be small enough to onlytrigger an immune response substantially against a SNAP-25 having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond, thus increasing the possibility of producing α-SNAP-25 antibodiesthat can distinguish a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond from a SNAP-25 lackinga carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond. Furthermore, it is also very desirable to generateα-SNAP-25 antibodies of a single amino acid sequence in a good yieldthat are reproducibly selective and which bind with acceptable avidityin order to permit the design of a highly sensitive assay.

The sequence surrounding a BoNT/A cleavage site present in SNAP-25 isdenoted as P₅-P₄-P₃-P₂-P₁-P₁′-P₂′-P₃′-P₄′-P₅′, with P₁-P₁′ representingthe scissile bond. Upon cleavage by retargeted endopeptidase, theresulting cleavage products produced comprise a fragment including theP₅-P₄-P₃-P₂-P₁ sequence and a fragment including theP₁′-P₂′-P₃′-P₄′-P₅′. Thus, as used herein, the term “SNAP-25 having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond” refers to any SNAP-25 having the P₁ residue as itscarboxyl-terminal amino acid. For example, Q₁₉₇-R₁₉₈ of human SNAP-25(SEQ ID NO:5) represents the P₁-P₁′ scissile bond for the BoNT/Acleavage site. As such, “SNAP-25 having a carboxyl-terminus glutamine ofthe BoNT/A cleavage site scissile bond” would be any SNAP-25 cleavageproduct having a glutamine at its carboxyl-terminal amino acid where theglutamine represents Q₁₉₇ of the scissile bond. As another example,K₂₀₄-H₂₀₅ of Torpedo marmorata SNAP-25 (SEQ ID NO:16) represents theP₁-P₁′ scissile bond for the BoNT/A cleavage site. As such, “SNAP-25having a carboxyl-terminus lysine of the BoNT/A cleavage site scissilebond” would be any SNAP-25 cleavage product having a lysine at itscarboxyl-terminal amino acid where the lysine represents K₂₀₄ of thescissile bond.

The SNAP-25 antigen having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond from the BoNT/A cleavage site can bemodified to enhance the immunogenicity of a SNAP-25 antigen, a hapten,or any other antigenic compound that is immunogenic, non-immunogenic, orweakly immunogenic when not associated with the modification. In anaspect of this embodiment, the carboxyl-terminal P₁ residue from thescissile bond of a SNAP-25 antigen can be carboxylated. Carboxylationincreases the desired immunogenic properties of a SNAP-25 antigen in tworespects. First, because charged amino acids enhance immunogenicity,adding a COO⁻ group to the carboxyl-terminal residue will increase theoverall immunogenicity of a SNAP-25 antigen. Second, because the P₁residue of the BoNT/A cleavage site scissile bond is in a charged stateupon cleavage, adding a COO⁻ group to the carboxyl-terminal residue willbetter mimic the actual antigen that the α-SNAP-25 antibodies disclosedin the present specification are designed to selectively bind.

In an aspect of this embodiment, the amino-terminal residue from aSNAP-25 antigen can be modified by the addition of an amino acid adaptedto attach the SNAP-25 antigen to a carrier protein, such as, e.g., akeyhole limpet hemacyanin (KLH), an ovalbumin (OVA), a thyroglobulin(THY), a bovine serum albumin (BSA), a soybean trypsin inhibitor (STI),or a multiple attachment peptide (MAP). For example, a cysteine residuecan be placed at the amino-terminus in order to conjugate the carrierprotein KLH.

Thus, an embodiment, a SNAP-25 antigen having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can be, e.g., atleast 5, at least 6, at least 7, at least 8, at least 9, at least 10, atleast 11, at least 12, at least 13, at least 14, at least 15, at least16, at least 17, at least 18, at least 19, at least 20, at least 25, orat least 30 amino acids in length. In another embodiment, a SNAP-25antigen having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond can be, e.g., at most 5, at most 6, at most7, at most 8, at most 9, at most 10, at most 11, at most 12, at most 13,at most 14, at most 15, at most 16, at most 17, at most 18, at most 19,at most 20, at most 25, or at most 30 amino acids in length. In stillanother embodiment, a SNAP-25 antigen having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can be, e.g.,between 7-12 amino acids, between 10-15 amino acids, or between 13-18amino acids.

In another embodiment, the SNAP-25 antigen having a carboxyl-terminus atthe P₁ residue of the BoNT/A cleavage site scissile bond comprises SEQID NO:33. In aspects of this embodiment, the SNAP-25 antigen having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond comprises SEQ ID NO:32, SEQ ID NO:34, SEQ ID NO:35, SEQ ID NO:36,SEQ ID NO:37, SEQ ID NO:38, or SEQ ID NO:39. In a further embodiment,the SNAP-25 antigen having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond comprises SEQ ID NO:40.

In yet another embodiment, the SNAP-25 antigen having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond comprises SEQ ID NO:41. In aspects of this embodiment, the SNAP-25antigen having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond comprises SEQ ID NO:42, SEQ ID NO:43, SEQ IDNO:44 SEQ ID NO:45, SEQ ID NO:46. In a further embodiment, the SNAP-25antigen having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond comprises SEQ ID NO:47.

It is envisioned that any and all SNAP-25 antigens that triggers animmune response that produces α-SNAP-25 antibodies that can selectivelybind to a SNAP-25 having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond can be useful as a SNAP-25 antigen.Thus, amino acid sequence variants comprising SEQ ID NO:32, SEQ IDNO:33, SEQ ID NO:34, SEQ ID NO:35, SEQ ID NO:36, SEQ ID NO:37, SEQ IDNO:38, SEQ ID NO:39, SEQ ID NO:41, SEQ ID NO:42, SEQ ID NO:43, SEQ IDNO:44, SEQ ID NO:45, or SEQ ID NO:46 can be useful as a SNAP-25 antigento trigger an immune response that produces α-SNAP-25 antibodies thatcan selectively bind to a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond. Thus, in anembodiment, a SNAP-25 antigen can substitute at least 1, at least 2, atleast 3, at least 4, or at least 5 amino acid substitutions, deletionsor additions to the SNAP-25 antigens comprising SEQ ID NO:32, SEQ IDNO:33, SEQ ID NO:34, SEQ ID NO:35, SEQ ID NO:36, SEQ ID NO:37, SEQ IDNO:38, SEQ ID NO:39, SEQ ID NO:41, SEQ ID NO:42, SEQ ID NO:43, SEQ IDNO:44, SEQ ID NO:45, or SEQ ID NO:46. In still another embodiment, aSNAP-25 antigen can have at least 70%, at least 75%, at least 80%, atleast 85%, at least 90%, or at least 95% amino acid identity to theSNAP-25 antigens comprising SEQ ID NO:32, SEQ ID NO:33, SEQ ID NO:34,SEQ ID NO:35, SEQ ID NO:36, SEQ ID NO:37, SEQ ID NO:38, SEQ ID NO:39,SEQ ID NO:41, SEQ ID NO:42, SEQ ID NO:43, SEQ ID NO:44, SEQ ID NO:45, orSEQ ID NO:46.

It is envisioned that one or more carriers may be linked to a SNAP-25antigen in order to enhance the immunogenicity of a SNAP-25 antigen thatis immunogenic, non-immunogenic, or weakly immunogenic when notassociated with the carrier. Non-limiting examples, include, e.g., akeyhole limpet hemacyanin (KLH), an ovalbumin (OVA), a thyroglobulin(THY), a bovine serum albumin (BSA), a soybean trypsin inhibitor (STI),or a multiple attachment peptide (MAP). As is well known in the art, anon-antigenic or weakly antigenic antigen can be made antigenic bycoupling the antigen to a carrier. Various other carrier and methods forcoupling an antigen to a carrier are well known in the art. See, e.g.,Harlow and Lane, supra, 1998a; Harlow and Lane, supra, 1998b; and DavidW. Waggoner, Jr. et al., Immunogenicity-enhancing carriers andcompositions thereof and methods of using the same, U.S. PatentPublication No. 20040057958 (Mar. 25, 2004). An epitope can also begenerated by expressing the epitope as a fusion protein. Methods forexpressing polypeptide fusions are well known to those skilled in theart as described, for example, in Ausubel et al., Current Protocols inMolecular Biology (Supplement 47), John Wiley & Sons, New York (1999).As the carboxyl-terminal end of the SNAP-25 antigen must be the P₁residue of the BoNT/A cleavage site scissile bond, a carrier must belinked to the amino end of the SNAP-25 antigen.

It is envisioned that one or more flexible spacers may be linked to aSNAP-25 antigen in order to enhance the immunogenicity of a SNAP-25antigen that is immunogenic, non-immunogenic, or weakly immunogenic whennot associated with the flexible linkers. A flexible spacer increasesthe overall peptide length of the SNAP-25 antigen and providesflexibility, thereby facilitating the proper presentation of the SNAP-25antigen to the immune cells. As a non-limiting example, a SNAP-25 immuneresponse inducing composition can comprise a SNAP-25 antigen linked toone or more flexible spacers in tandem to better present SNAP-25 antigento immune cells, thereby facilitating the immune response.

A flexible space comprising a peptide is at least one amino acid inlength and comprises non-charged amino acids with small side-chain Rgroups, such as, e.g., glycine, alanine, valine, leucine or serine.Thus, in an embodiment a flexible spacer can be, e.g., at least 1, atleast 2, at least 3, at least 4, at least 5, at least 6, at least 7, atleast 8, at least 9, or at least 10 amino acids in length. In anotherembodiment, a flexible spacer can be, e.g., at least 1, at most 2, atmost 3, at most 4, at most 5, at most 6, at most 7, at most 8, at most9, or at most 10 amino acids in length. In still another embodiment, aflexible spacer can be, e.g., between 1-3 amino acids, between 2-4 aminoacids, between 3-5 amino acids, between 4-6 amino acids, or between 5-7amino acids. Non-limiting examples of a flexible spacer include, e.g., aG-spacers such as GGG, GGGG (SEQ ID NO:57), and GGGGS (SEQ ID NO:58) oran A-spacers such as AAA, AAAA (SEQ ID NO:59) and AAAAV (SEQ ID NO:60).A flexible spacer is linked in-frame to the SNAP-25 antigen as a fusionprotein.

As discussed above, a flexible spacer is used, in part, to increase theoverall peptide length of the SNAP-25 antigen. For example, a 5-10 aminoacid SNAP-25 antigen can have its overall length increased by linking a3-5 amino acid flexible space to the amino-end of the SNAP-25 antigen.As another example, a 5-10 amino acid SNAP-25 antigen can have itsoverall length increased by linking a 4-6 amino acid flexible space tothe amino-end of the SNAP-25 antigen. As another example, a 5-10 aminoacid SNAP-25 antigen can have its overall length increased by linking a7-10 amino acid flexible space to the amino-end of the SNAP-25 antigen.As another example, a 7-12 amino acid SNAP-25 antigen can have itsoverall length increased by linking a 1-3 amino acid flexible space tothe amino-end of the SNAP-25 antigen. As another example, a 7-12 aminoacid SNAP-25 antigen can have its overall length increased by linking a4-6 amino acid flexible space to the amino-end of the SNAP-25 antigen.The increased length provided by the flexible spacer allows for theselection of a small sized SNAP-25 antigen, thereby increasing thelikelihood that the SNAP-25 antigen will only trigger an immune responsesubstantially against a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond, thus increasing thepossibility of producing α-SNAP-25 antibodies that can distinguish aSNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond from a SNAP-25 lacking a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond.

It is envisioned that a SNAP-25 immune response inducing compositiondisclosed in the present specification can optionally comprise a SNAP-25antigen disclosed in the present specification and one or moreadjuvants. As used herein, the term “adjuvant” when used in reference toa SNAP-25 immune response inducing composition refers to any substanceor mixture of substances that increases or diversifies the immuneresponse to a SNAP-25 antigen. An immune response inducing adjuvant can,for example, serve to reduce the number of immunizations or the amountof antigen required for protective immunization. The use of immuneresponse inducing adjuvants in an immune response inducing compositionis well known. The main objective of these adjuvants is to allow anincrease in the immune response. Non-limiting adjuvants include, e.g.,liposomes, oily phases, including, without limitation, the Freund typeof adjuvants, such as, e.g., Freund's complete adjuvant (FCA); Freund'sincomplete adjuvant (FIA); sapogenin glycosides, such as, e.g.,saponins; carbopol; N-acetylmuramyl-L-alanyl-D-isoglutamine (commonlyknown as muramyl dipeptide or “MDP”); and lipopolysaccharide (LPS). Suchadjuvants are generally used in the form of an emulsion with an aqueousphase, or, more commonly, may consist of water-insoluble inorganicsalts. These inorganic salts may consist, for example, of aluminumhydroxide, zinc sulfate, colloidal iron hydroxide, calcium phosphate orcalcium chloride. Aluminum hydroxide (Al(OH)₃) is a commonly usedadjuvant. Currently, the only FDA-approved adjuvant for use in humans isaluminum salts (Alum) which are used to “depot” antigens byprecipitation of the antigens. Adjuvants provided above are merelyexemplary. In fact, any immune response inducing adjuvant may be used inan immune response inducing composition disclosed in the presentspecification as long as the adjuvant satisfies the requisitecharacteristics for inducing an immune response.

A carrier disclosed in the present specification may also act as anadjuvant. Specific adjuvants and methods of making and using aredescribed in, e.g., Gupta et al. Vaccine, 11: 993-306, 1993; Arnon, R.(Ed.) Synthetic Vaccines 1:83-92, CRC Press, Inc., Boca Raton, Fla.,1987; and David W. Waggoner, Jr. et al., Immunogenicity-EnhancingCarriers and Compositions Thereof and Methods of Using the Same, U.S.Patent Publication No. 20040057958 (Mar. 25, 2004). Additional adjuvantsinclude any compound described in Chapter 7 (pp 141-227) of “VaccineDesign, The Subunit and Adjuvant Approach” (eds. Powell, M. F. andNewman, M. J.) Pharmaceutical Biotechnology, Volume 6, Plenum Press (NewYork). Examples from this compendium include Muramyl Dipeptide (MDP) andMontanide 720. Molecules such as Poly Inosine:Cytosine (Poly I:C) orplasmid DNA containing CpG motifs can also be administered as adjuvantsin combination with antigens encapsulated in microparticles. In anotherexample, the adjuvant is an agent that facilitates entry of theantigenic compound into the cytoplasm of a cell such as listeriolysin,streptolysin or a mixture thereof.

Thus, in an embodiment, a SNAP-25 immune response inducing compositioncomprises a SNAP-25 antigen having a carboxylated carboxyl-terminalglutamine linked to a carrier peptide. In aspects of this embodiment, aSNAP-25 antigen having a carboxylated carboxyl-terminal glutaminecomprises SEQ ID NO:32, SEQ ID NO:33, SEQ ID NO:34, SEQ ID NO:35, SEQ IDNO:36, SEQ ID NO:37, SEQ ID NO:38, or SEQ ID NO:39. In another aspect ofthis embodiment, a SNAP-25 antigen comprises SEQ ID NO:40. In aspects ofthis embodiment, the carrier peptide is a keyhole limpet hemacyanin(KLH), an ovalbumin (OVA), a thyroglobulin (THY), a bovine serum albumin(BSA), a soybean trypsin inhibitor (STI) or a multiple attachmentpeptide (MAP).

In another embodiment, a SNAP-25 immune response inducing compositioncomprises a SNAP-25 antigen having a carboxylated carboxyl-terminallysine linked to a carrier peptide. In aspects of this embodiment,SNAP-25 antigen having a carboxylated carboxyl-terminal lysine comprisesSEQ ID NO:41, SEQ ID NO:42, SEQ ID NO:43, SEQ ID NO:44, SEQ ID NO:45, orSEQ ID NO:46. In another aspect of this embodiment, a SNAP-25 antigencomprises SEQ ID NO:47. In aspects of this embodiment, the carrierpeptide is a keyhole limpet hemacyanin (KLH), an ovalbumin (OVA), athyroglobulin (THY), a bovine serum albumin (BSA), a soybean trypsininhibitor (STI) or a multiple attachment peptide (MAP).

In yet another embodiment, a SNAP-25 immune response inducingcomposition comprises a SNAP-25 antigen having a carboxylated C-terminalglutamine linked to one or more flexible linkers and a carrier peptidewherein the flexible linkers intervene between the SNAP-25 antigen andthe carrier peptide. In aspects of this embodiment, SNAP-25 antigenhaving a carboxylated carboxyl-terminal glutamine comprises SEQ IDNO:32, SEQ ID NO:33, SEQ ID NO:34, SEQ ID NO:35, SEQ ID NO:36, SEQ IDNO:37, SEQ ID NO:38, or SEQ ID NO:39. In another embodiment, a SNAP-25antigen comprises SEQ ID NO:46. In aspects of this embodiment, thecarrier peptide is a keyhole limpet hemacyanin (KLH), an ovalbumin(OVA), a thyroglobulin (THY), a bovine serum albumin (BSA), a soybeantrypsin inhibitor (STI) or a multiple attachment peptide (MAP). Inaspects of this embodiment, the flexible linker is a G-spacer or anA-spacer.

In still another embodiment, a SNAP-25 immune response inducingcomposition comprises a SNAP-25 antigen having a carboxylated C-terminallysine linked to a flexible linker and a carrier peptide wherein theflexible linker intervenes between the SNAP-25 antigen and the carrierpeptide. In aspects of this embodiment, SNAP-25 antigen having acarboxylated carboxyl-terminal lysine comprises SEQ ID NO:41, SEQ IDNO:42, SEQ ID NO:43, SEQ ID NO:44, SEQ ID NO:45, or SEQ ID NO:46. Inanother aspect of this embodiment, a SNAP-25 antigen comprises SEQ IDNO:47. In aspects of this embodiment, the carrier peptide is a keyholelimpet hemacyanin (KLH), an ovalbumin (OVA), a thyroglobulin (THY), abovine serum albumin (BSA), a soybean trypsin inhibitor (STI) or amultiple attachment peptide (MAP). In aspects of this embodiment, theflexible linker is a G-spacer or an A-spacer.

Aspects of the present disclosure comprise, in part, a method forproducing α-SNAP-25 antibodies that can selectively bind to a SNAP-25having a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond. An α-SNAP-25 antibody that selectively binds to a SNAP-25epitope having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond can be produced by a wide variety of methodsthat are well known in the art. Specific protocols for making and usingantibodies as well as detecting, and measuring antibody bindingspecificity, binding affinity and binding avidity are known in the art.See, e.g., ANTIBODIES: A LABORATORY MANUAL (Edward Harlow & David Lane,eds., Cold Spring Harbor Laboratory Press, 2^(nd) ed. 1998a); and USINGANTIBODIES: A LABORATORY MANUAL: PORTABLE PROTOCOL No. I (Edward Harlow& David Lane, Cold Spring Harbor Laboratory Press, 1998b); MolecularCloning, A Laboratory Manual, 2001; and Current Protocols in MolecularBiology, 2004; David Anderson et al., Therapeutic Polypeptides, NucleicAcids Encoding Same, and Methods of Use, U.S. Pat. No. 7,034,132 (Apr.25, 2005); and Beatriz M. Carreno et al., Antibodies Against CTLA4, U.S.Pat. No. 7,034,121 (Apr. 25, 2006).

As a non-limiting example, α-SNAP-25 polyclonal antibodies thatselectively bind to a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond can be produced byinjecting an animal, such as, e.g., a rabbit, a goat, a mouse or anothermammal, with one or more injections of an immune response inducingcomposition disclosed in the present specification. As anothernon-limiting example, α-SNAP-25 polyclonal antibodies that selectivelybind to a SNAP-25 having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond can be produced by injecting an egg,such as, e.g., a chicken egg, with one or more injections of an immuneresponse inducing composition disclosed in the present specification.The antibody titer in the immunized animal can be monitored over time bystandard techniques, such as with an enzyme linked immunosorbent assay(ELISA) using immobilized antigen or a cell-based activity assay. Ifdesired, polyclonal antibodies for an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can be isolatedfrom the mammal (e.g., from the blood) and further purified by wellknown techniques, such as protein A affinity chromatography to obtainthe IgG fraction, or by affinity purification against the peptide usedfor producing the antibodies.

As another non-limiting example, α-SNAP-25 monoclonal antibody thatselectively binds to a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond can be produced usinga hybridoma method. See e.g., Chapter 6 Monoclonal Antibodies, pp.196-244, Harlow & Lane, supra, 1998a; and Chapter 7 Growing Hybridomas,pp. 245-282, Harlow & Lane, supra, 1998a; and Goding, pp. 59-103,Monoclonal Antibodies: Principles and Practice, Academic Press, (1986).In this method, a host animal, such as, e.g., a mouse, a hamster, oranother appropriate host animal, is typically exposed to one or moreinjections of a SNAP-25 antigen disclosed in the present specificationto elicit lymphocytes that produce or are capable of producing α-SNAP-25antibodies that will specifically bind to a SNAP-25 having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond. The antibody titer in the immunized animal can be monitored overtime by standard techniques, such as with an enzyme linked immunosorbentassay (ELISA) using immobilized antigen or a cell-based activity assay.Alternatively, the lymphocytes can be immunized in vitro using asuitable cell culture line. At an appropriate time after immunization,e.g., when the antibody titers are highest, antibody-producing cells areisolated from the animal. Generally, either peripheral blood lymphocytesare used, if cells of human origin are desired, or spleen cells or lymphnode cells are used, if non-human mammalian sources are desired. Theisolated antibody-producing cells are fused with an immortal cell lineusing a suitable fusing agent, such as polyethylene glycol, to form ahybridoma cell. Immortalized cell lines are usually transformedmammalian cells, particularly myeloma cells of rodent, bovine and humanorigin. Typically, a murine myeloma cell line is fused with splenocytesharvested from an appropriately immunized mouse to produce thehybridoma. Preferred immortal cell lines are mouse myeloma cell linesthat are sensitive to culture medium containing hypoxanthine,aminopterin and thymidine (HAT). Any of a number of myeloma cell linescan be used as a fusion partner according to standard techniques, e.g.,the P3-NS1/1-Ag4-1, P3-x63-Ag8.653 or Sp2/O-Ag14 myeloma lines.Hybridoma cells resulting from the fusion are then selected using HATmedium, which kills unfused and unproductively fused myeloma cells(unfused splenocytes die after several days in culture because they arenot transformed). The culture medium in which the hybridoma cells aregrown can then be assayed for the presence of α-SNAP-25 monoclonalantibodies that selectively bind to a SNAP-25 having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond. Forexample, hybridoma supernatants can be screened using α-SNAP-25 positivemedia in an immunoprecipitation assay, in vitro binding assay, such as,e.g., a radioimmunoassay (RIA) or an enzyme-linked immunoabsorbent assay(ELISA), or in a cell-based activity assay. Such techniques and assaysare known in the art. See e.g., Chapter 11 Immunoprecipitation, pp.421-470, Harlow & Lane, supra, 1998a; Chapter 12 Immunoblotting, pp.471-510, Harlow & Lane, supra, 1998a; Chapter 14 Immunoassays, pp.553-612, Harlow & Lane, supra, 1998a. Additional studies can then bedone to determine whether the antibody is also unreactive to a SNAP-25lacking a carboxyl-terminus at the P₁ residue of the BoNT/A cleavagesite scissile bond. The binding affinity of an α-SNAP-25 monoclonalantibody can also be determined, e.g., by Scatchard analysis. See, e.g.,Peter J. Munson and David Rodbard, Ligand: A Versatile ComputerizedApproach For Characterization of Ligand-Binding Systems, 107 (1) Anal.Biochem. 220-239 (1980). After the desired hybridoma cells areidentified, limiting dilution procedures are used to isolate clonesoriginating from a single cell until a clonal cell line expressing thedesired monoclonal antibody is obtained. Those antibodies sufficientlyselective for a SNAP-25 having a carboxyl-terminus at the P₁ residue ofthe BoNT/A cleavage site scissile bond and bind with sufficiently highavidity are chosen for further characterization and study.

Another alternative for preparing an α-SNAP-25 monoclonal antibody thatselectively binds to a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond is by screening arecombinant combinatorial immunoglobulin library, such as, e.g., anantibody phage display library, with a SNAP-25 peptide and isolateimmunoglobulin library members that bind a SNAP-25 having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond. Kits for generating and screening phage display libraries arecommercially available, such as, e.g., the Recombinant Phage AntibodySystem (Amersham GE Healthcare, Piscataway, N.J.); and the SurfZAP™Phage Display Kit (Stratagene, La Jolla, Calif.). Additionally, examplesof methods and reagents useful in generating and screening antibodydisplay library can be found in, for example, Ladner et al. U.S. Pat.No. 5,223,409; Borrebaeck et al. U.S. Pat. No. 5,712,089; Griffiths etal. U.S. Pat. No. 5,885,793; Griffiths et al. U.S. Pat. No. 5,962,255;McCafferty et al. U.S. Pat. No. 5,969,108; Griffiths et al. U.S. Pat.No. 6,010,884; Jespers et al. U.S. Pat. No. 6,017,732; Borrebaeck et al.U.S. Pat. No. 6,027,930; Johnson et al. U.S. Pat. No. 6,140,471;McCafferty et al. U.S. Pat. No. 6,172,197, each of which is herebyincorporated by reference in its entirety.

Aspects of the present disclosure comprise, in part, collecting a samplecontaining an α-SNAP-25 antibody or α-SNAP-25 antibody-producing cells.As used herein, the term “sample containing an α-SNAP-25 antibody orα-SNAP-25 antibody-producing cell” refers to any biological matter thatcontains or potentially contains at least one an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond. It is envisionedthat any and all samples that can contain an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can be used in thismethod, including, without limitation, blood, plasma, serum and lymphfluid. It is also envisioned that any cell capable of producing anα-SNAP-25 antibody that selectively binds to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond can be used in this method, including, without limitation, a CD8cells, a CTL cell, a helper T-cell and a B-cell. A variety of well knownmethods can be used for collecting from an individual a samplecontaining the α-SNAP-25 antibody or α-SNAP-25 antibody-producing cell,see, e.g., Harlow & Lane, supra, 1998a; and Harlow & Lane, supra, 1998b.Similarly, a variety of well known methods can be used for processing asample to isolate an α-SNAP-25 antibody that selectively binds to aSNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond. A procedure for collecting a samplecan be selected based on the type of antibody to be isolated. As anon-limiting example, when isolating an α-SNAP-25 polyclonal antibodiesthat selectively bind to a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond, an appropriate samplecan be a blood sample containing such α-SNAP-25 antibodies, whereas whenisolating an α-SNAP-25 monoclonal antibodies that selectively bind to aSNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond, an appropriate sample can be an α-SNAP-25antibody-producing cell such as a spleen cell or hybridoma.

Aspects of the present disclosure comprise, in part, isolating anα-SNAP-25 antibody that selectively binds to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond from the sample. Methods of isolating an such α-SNAP-25 antibodies,such as, e.g., α-SNAP-25 polyclonal antibodies that selectively bind toa SNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond or α-SNAP-25 monoclonal antibodies thatselectively bind to a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond are well known tothose skilled in the art. See, e.g., Harlow and Lane, supra, 1998a; andHarlow and Lane, supra, 1998b. For example, such α-SNAP-25 polyclonalantibodies can be isolated from the sample by well known techniques,such as, e.g., affinity chromatography using protein A or protein G,which provide primarily the IgG fraction of immune serum. Subsequently,or alternatively, a specific SNAP-25 antigen can be immobilized on acolumn or magnetic beads to purify the α-SNAP-25 polyclonal antibodiesthat selectively binds to a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond by immunoaffinitychromatography. An α-SNAP-25 monoclonal antibody that selectively bindsto a SNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond can be isolated from the culture medium orascites fluid by conventional immunoglobulin purification proceduressuch as, e.g., protein A-Sepharose, hydroxylapatite chromatography, gelelectrophoresis, dialysis, or affinity chromatography.

Thus, in an embodiment, a method of producing a α-SNAP-25 antibody thatcan selectively bind to a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond comprises the steps(a) administering to an animal a SNAP-25 immune response inducingcomposition comprising a SNAP-25 antigen having a carboxylatedC-terminal glutamine linked to a carrier peptide; (b) collecting fromthe animal a sample containing an α-SNAP-25 antibody or α-SNAP-25antibody-producing cell; and (c) isolating the α-SNAP-25 antibodycomponent from the sample. In an aspect of this embodiment, theα-SNAP-25 antibody that can selectively bind to a SNAP-25 having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond is a polyclonal antibody. In another aspect of this embodiment,α-SNAP-25 antibody that can selectively bind to a SNAP-25 having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond is a monoclonal antibody. In a further aspect of this embodiment,an α-SNAP-25 monoclonal antibody that can selectively bind to a SNAP-25having a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond produced is an IgG subtype. In other aspects of thisembodiment, SNAP-25 immune response inducing composition furthercomprises an adjuvant, such as, e.g., polyethylene glycol (PEG),monomethoxypolyethylene glycol (mPEG), or polyvinyl alcohol (PVA).

In another embodiment, a method of producing α-SNAP-25 antibodies thatcan selectively bind to a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond comprises the steps(a) administering to an animal a SNAP-25 immune response inducingcomposition comprising a SNAP-25 peptide having a carboxylatedC-terminal glutamine linked to a flexible linker and a carrier peptidewherein the flexible linker intervenes between the SNAP-25 peptide andthe carrier peptide; (b) collecting from the animal a sample containingan α-SNAP-25 antibody or α-SNAP-25 antibody-producing cell; and (c)isolating the α-SNAP-25 antibody from the sample. In an aspect of thisembodiment, the α-SNAP-25 antibodies that can selectively bind to aSNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond is a polyclonal antibody. In another aspectof this embodiment, α-SNAP-25 antibodies that can selectively bind to aSNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond is a monoclonal antibody. In a furtheraspect of this embodiment, α-SNAP-25 monoclonal antibody that canselectively bind to a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond produced in an IgGsubtype. In other aspects of this embodiment, SNAP-25 immune responseinducing composition further comprises an adjuvant, such as, e.g.,polyethylene glycol (PEG), monomethoxypolyethylene glycol (mPEG), orpolyvinyl alcohol (PVA).

Aspects of the present disclosure comprise, in part, an isolatedα-SNAP-25 antibody that selectively binds to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond. As used herein, the term “antibody” refers to a molecule generatedby an immune system that was made in response to a particular antigenthat specifically binds to that antigen, and includes both naturallyoccurring antibodies and non-naturally occurring antibodies. As usedherein, the term “isolated” refers to separating a molecule from itsnatural environment by the use of human intervention. For example, anantibody can be a polyclonal antibody, a monoclonal antibody, a dimer, amultimer, a multispecific antibody, a humanized antibody, a chimericantibody, bi-functional antibody, a cell-associated antibody like an Igreceptor, a linear antibody, a diabody, or a minibody, so long as thefragment exhibits the desired biological activity, and single chainderivatives of the same. An antibody can be a full-length immunoglobulinmolecule comprising the V_(H) and V_(L) domains, as well as a lightchain constant domain (C_(L)) and heavy chain constant domains, C_(H1),C_(H2) and C_(H3), or an immunologically active fragment of afull-length immunoglobulin molecule, such as, e.g., a Fab fragment, aF(ab′)₂ fragment, a Fc fragment, a Fd fragment, a Fv fragment. Anantibody can be derived from any vertebrate species (e.g., human, goat,horse, donkey, murine, rat, rabbit, or chicken), and can be of any type(e.g., IgG, IgE, IgM, IgD, and IgA), class (e.g., IgA, IgD, IgE, IgG,and IgM) or subclass (IgG1, IgG2, IgG3, IgG4, IgA1 and IgA2). Forgeneral disclosure on the structure of naturally occurring antibodies,non-naturally occurring antibodies, and antigenic compound-bindingfragments thereof, see, e.g., Pluckthun in The Pharmacology ofMonoclonal Antibodies, vol. 113, Rosenburg and Moore eds.,Springer-Verlag, New York, pp. 269-315 (1994); Borrabeck, AntibodyEngineering, 2d ed. (Oxford University Press 1995), each of which ishereby incorporated by reference in its entirety.

Naturally-occurring antibodies are usually heterotetramericglycoproteins of about 150,000 daltons, composed of two identical light(L) chains and two identical heavy (H) chains. Each light chain islinked to a heavy chain by one covalent disulfide bond, while the numberof disulfide linkages varies among the heavy chains of differentimmunoglobulin isotypes. Each heavy and light chain also has regularlyspaced intrachain disulfide bridges. Each heavy chain has at one end avariable domain (V_(H)) followed by a number of constant domains. Eachlight chain has a variable domain at one end (V_(L)) and a constantdomain at its other end. The constant domain of the light chain isaligned with the first constant domain of the heavy chain, and thelight-chain variable domain is aligned with the variable domain of theheavy chain. Particular amino acid residues are believed to form aninterface between the light chain and heavy chain variable domains.

The complete antigen-recognition and antigen-binding site is containedwithin the variable domains of the antibody, i.e., the Fv fragment. Thisfragment includes a dimer of one heavy chain variable domain (V_(H)) andone light chain variable domain (V_(L)) in tight, non-covalentassociation. Each domain comprises four framework regions (FR), whichlargely adopting a β-sheet configuration, connected by threehypervariable regions, which form loops connecting, and in some casesform part of, the β-sheet structure. Each hypervariable region comprisesan amino acid sequence corresponding to a complementarity determiningregion (CDRs). Collectively, it the three-dimensional configuration ofthe six CDR regions that define an antigen-binding site on the surfaceof the V_(H)-V_(L) dimmer that confers antigen-binding specificity. Seee.g., Cyrus Chothia, et al., Conformations of ImmunoglobulinHypervariable Regions, Nature 342(6252): 877-883 (1989); Elvin A. Kabat,et al Sequences of Proteins of Immunological Interest, 5th Ed. PublicHealth Service, National Institutes of Health, Bethesda, Md. (1991),each of which is incorporated by reference in its entirety. The constantdomains of the antibody are not involved directly in binding an antibodyto an antigen, but exhibit various effector functions, such asparticipation of the antibody in antibody dependent cellularcytotoxicity.

A target antigen generally has one or more binding sites, also calledepitopes, which are recognized by the CDR-formed antigen-binding site.As used herein, an “epitope” is synonymous with “antigenic determinant”and refers to the site on a target antigen, such as, e.g., a peptide,polysaccharide or lipid-containing molecule, capable of specific bindingto an immunoglobulin or T-cell receptor or otherwise interacting with amolecule. Each antibody that specifically binds to a different epitopehas a different structure. Thus, one antigen may have more than onecorresponding antibody.

Polyclonal antibodies refer to a heterogeneous population of antibodymolecules that contain at least two species of antibody capable ofbinding to a particular antigen. By definition, a polyclonal antibodyincludes two different antibodies that bind to at least two differentepitopes. As used herein, the term “monoclonal antibody” or “monoclonalantibodies” refer to a substantially homogeneous population of antibodymolecules that contain only one species of antibody capable of binding aparticular antigen i.e., the individual antibodies comprising thepopulation are identical except for possible naturally occurringmutations that may be present in minor amounts. By definition, amonoclonal antibody binds to a single epitope. Monoclonal antibodies arehighly specific, being directed against a single antigenic site.Furthermore, in contrast to polyclonal antibodies, each monoclonalantibody is directed against a single determinant on the antigen. Inaddition to their specificity, the monoclonal antibodies areadvantageous in that they may be synthesized uncontaminated by otherantibodies. The modifier “monoclonal” indicates the character of theantibody as being obtained from a substantially homogeneous populationof antibodies, and is not to be construed as requiring production of theantibody by any particular method. For example, the monoclonalantibodies to be used in accordance with the present disclosure may bemade by the hybridoma method first described by Kohler et al (1975)Nature 256:495, or may be made by recombinant DNA methods (see forexample: U.S. Pat. No. 4,816,567; U.S. Pat. No. 5,807,715). Themonoclonal antibodies may also be isolated from phage antibody librariesusing the techniques described in Clackson et al (1991) Nature,352:624-628; Marks et al (1991) J. Mol. Biol., 222:581-597; for example.

Thus, in an embodiment, an α-SNAP-25 antibody comprises a heavy chainvariable domain (V_(H)) and a light chain variable domain (V_(L)) thatselectively binds to a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond. In an aspect of thisembodiment, the heavy chain variable domain (V_(H)) is SEQ ID NO:72, SEQID NO:74, SEQ ID NO:76, SEQ ID NO:80, SEQ ID NO:82, or SEQ ID NO:133. Inanother aspect of this embodiment, the light chain variable domain(V_(L)) is SEQ ID NO:84, SEQ ID NO:86, SEQ ID NO:88, SEQ ID NO:90, orSEQ ID NO:92.

In another embodiment, a nucleic acid sequence encodes an α-SNAP-25antibody comprising a heavy chain variable domain (V_(H)) and a lightchain variable domain (V_(L)) that selectively binds to a SNAP-25 havinga carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond. In an aspect of this embodiment, the heavy chain variabledomain (V_(H)) is encoded by the nucleic acid sequence SEQ ID NO:71, SEQID NO:73, SEQ ID NO:75, SEQ ID NO:77, SEQ ID NO:79, SEQ ID NO:81, or SEQID NO:132. In another aspect of this embodiment, the heavy chainvariable domain (V_(H)) is encoded by a nucleic acid sequence that is atleast 70% identical to, at least 75% identical to, at least 80%identical to, at least 85% identical to, at least 90% identical to, atleast 95% identical, at least 96% identical, at least 97% identical, atleast 98% identical, or at least 99% identical to SEQ ID NO:71, SEQ IDNO:73, SEQ ID NO:75, SEQ ID NO:77, SEQ ID NO:79, SEQ ID NO:81, or SEQ IDNO:132. In yet another aspect of this embodiment, the light chainvariable domain (V_(L)) is encoded by SEQ ID NO:83, SEQ ID NO:85, SEQ IDNO:87, SEQ ID NO:89, or SEQ ID NO:91. In still another aspect of thisembodiment, the light chain variable domain (V_(L)) is encoded by anucleic acid sequence that is at least 70% identical to, at least 75%identical to, at least 80% identical to, at least 85% identical to, atleast 90% identical to, at least 95% identical, at least 96% identical,at least 97% identical, at least 98% identical, or at least 99%identical to SEQ ID NO:83, SEQ ID NO:85, SEQ ID NO:87, SEQ ID NO:89, orSEQ ID NO:91.

In another embodiment, an α-SNAP-25 antibody comprises a heavy chainvariable domain (V_(H)) CDR1 region, a CDR2 region, a CDR3 region, orany combination thereof that selectively binds to a SNAP-25 having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond. In an aspect of this embodiment, the heavy chain variable domain(V_(H)) CDR1 region is SEQ ID NO:93, SEQ ID NO:94, SEQ ID NO:95, SEQ IDNO:118, SEQ ID NO:119, or SEQ ID NO:120. In another aspect of thisembodiment, the heavy chain variable domain (V_(H)) CDR2 region is SEQID NO:96, SEQ ID NO:97, SEQ ID NO:98, SEQ ID NO:99, SEQ ID NO:121, SEQID NO:122, or SEQ ID NO:123. In yet another aspect of this embodiment,the heavy chain variable domain (V_(H)) CDR3 region is SEQ ID NO:100,SEQ ID NO:101, SEQ ID NO:102, SEQ ID NO:124, SEQ ID NO:134, or SEQ IDNO:135.

In another embodiment, an α-SNAP-25 antibody comprises a light chainvariable domain (V_(L)) CDR1 region, a CDR2 region, a CDR3 region, orany combination thereof that selectively binds to a SNAP-25 having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond. In an aspect of this embodiment, the light chain variable domain(V_(L)) CDR1 region is SEQ ID NO:103, SEQ ID NO:104, SEQ ID NO:105, SEQID NO:106, SEQ ID NO:107, SEQ ID NO:125, SEQ ID NO:126, SEQ ID NO:127,SEQ ID NO:128, or SEQ ID NO:129. In another aspect of this embodiment,the light chain variable domain (V_(L)) CDR2 region is SEQ ID NO:108,SEQ ID NO:109, SEQ ID NO:110, SEQ ID NO:111, or SEQ ID NO:112. In yetanother aspect of this embodiment, the light chain variable domain(V_(L)) CDR3 region is SEQ ID NO:113, SEQ ID NO:114, SEQ ID NO:115, SEQID NO:116, or SEQ ID NO:117.

In yet another embodiment, an α-SNAP-25 antibody specifically binds anepitope comprising a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond. In an aspect of thisembodiment, the epitope comprises SEQ ID NO:32, SEQ ID NO:33, SEQ IDNO:34, SEQ ID NO:35, SEQ ID NO:36, or SEQ ID NO:37. In an aspect of thisembodiment, the epitope comprises SEQ ID NO:39, SEQ ID NO:40, SEQ IDNO:41, SEQ ID NO:42, SEQ ID NO:43, or SEQ ID NO:44.

As discussed above, the sequence surrounding a BoNT/A cleavage sitepresent in SNAP-25 is denoted P₅-P₄-P₃-P₂-P₁-P₁′-P₂′-P₃′-P₄′-P₅′, withP₁-P₁′ representing the scissile bond. Upon cleavage by BoNT/A, theresulting cleavage products produced comprise a fragment including theP₅-P₄-P₃-P₂-P₁ sequence and a fragment including theP₁′-P₂′-P₃′-P₄′-P₅′. As used herein, the term “α-SNAP-25 antibodies thatselectively bind to a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond” refers to α-SNAP-25antibodies that selectively bind to any SNAP-25 cleavage productfragment comprising the P₅-P₄-P₃-P₂-P₁ sequence, but not to any SNAP-25cleavage product fragment comprising the P₁′-P₂′-P₃′-P₄′-P₅′ sequence orto any SNAP-25 having an intact P₁-P₁′ scissile bond of a BoNT/Acleavage site. As used herein, the term “α-SNAP-25₁₉₇ antibody” refersto an antibody that selectively binds to a SNAP-25 having acarboxyl-terminus P₁ residue that corresponds to glutamine 197 of SEQ IDNO:5. As used herein, the term “α-SNAP-25₂₀₄ antibody” refers to anantibody that selectively binds to a SNAP-25 having a carboxyl-terminusP₁ residue that corresponds to lysine 204 of SEQ ID NO:16.

As used herein, the term “selectively” refers to having a unique effector influence or reacting in only one way or with only one thing. As usedherein, the term “selectively binds”, or “selective binding” when madein reference to an antibody, refers to the discriminatory binding of theantibody to the indicated target epitope such that the antibody does notsubstantially cross react with non-target epitopes. The minimal size ofa peptide epitope, as defined herein, is about five amino acids, and apeptide epitope typically comprises at least 5, at least 6, at least 7,at least 8, at least 9, at least 10, at least 15, or at least 20 aminoacids. A peptide epitope may be discontinuous, i.e., it comprises aminoacid residues that are not adjacent in the primary structure of thepeptide but are brought together into an epitope by way of thesecondary, tertiary, or quaternary structure of the peptide.Furthermore, it is also noted that an epitope might comprise a portionof a molecule other than an amino acid sequence, such as, e.g., acarbohydrate moiety, a lipid moiety like lipoproteins or glycolipids, ora chemically-modified amino acid moiety like a phosphorylated aminoacid. In aspects of this embodiment, an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can selectivelybind a SNAP-25 epitope having a carboxyl-terminus at the P₁ residue ofthe BoNT/A cleavage site scissile bond comprising at least 5, at least6, at least 7, at least 8, at least 9, at least 10, at least 15, or atleast 20 amino acids. In other aspects of this embodiment, an α-SNAP-25antibody that selectively binds to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond can selectively bind a SNAP-25 epitope having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond comprisingat most 5, at most 6, at most 7, at most 8, at most 9, at most 10, atmost 15, or at most 20 amino acids.

Selective binding includes binding properties such as, e.g., bindingaffinity, binding specificity, and binding avidity. See David J. King,Applications and Engineering of Monoclonal Antibodies, pp. 240 (1998).Binding affinity refers to the length of time the antibody resides atits epitope binding site, and can be viewed as the strength with whichan antibody binds its epitope. Binding affinity can be described anantibody's equilibrium dissociation constant (KD), which is defined asthe ratio Kd/Ka at equillibrium. Where Ka is the antibody's associationrate constant and kd is the antibody's dissociation rate constant.Binding affinity is determined by both the association and thedissociation and alone neither high association or low dissociation canensure high affinity. The association rate constant (Ka), or on-rateconstant (Kon), measures the number of binding events per unit time, orthe propensity of the antibody and the antigen to associate reversiblyinto its antibody-antigen complex. The association rate constant isexpressed in M⁻¹ s⁻¹, and is symbolized as follows: [Ab]×[Ag]×Kon. Thelarger the association rate constant, the more rapidly the antibodybinds to its antigen, or the higher the binding affinity betweenantibody and antigen. The dissociation rate constant (Kd), or off-rateconstant (Koff), measures the number of dissociation events per unittime propensity of an antibody-antigen complex to separate (dissociate)reversibly into its component molecules, namely the antibody and theantigen. The dissociation rate constant is expressed in s⁻¹, and issymbolized as follows: [Ab+Ag]×Koff. The smaller the dissociation rateconstant, the more tightly bound the antibody is to its antigen, or thehigher the binding affinity between antibody and antigen. Theequilibrium dissociation constant (KD) measures the rate at which newantibody-antigen complexes formed equals the rate at whichantibody-antigen complexes dissociate at equilibrium. The equilibriumdissociation constant is expressed in M, and is defined asKoff/Kon=[Ab]×[Ag]/[Ab+Ag], where [Ab] is the molar concentration of theantibody, [Ag] is the molar concentration of the antigen, and [Ab+Ag] isthe of molar concentration of the antibody-antigen complex, where allconcentrations are of such components when the system is at equilibrium.The smaller the equilibrium dissociation constant, the more tightlybound the antibody is to its antigen, or the higher the binding affinitybetween antibody and antigen.

Thus, in an embodiment, the binding affinity of an α-SNAP-25 antibodythat selectively binds to a SNAP-25 epitope having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond can have anassociation rate constant of, e.g., less than 1×10⁵ M⁻¹ s⁻¹, less than1×10⁶ M⁻¹ s⁻¹, less than 1×10⁷ M⁻¹ s⁻¹, or less than 1×10⁸ M⁻¹ s⁻¹. Inanother embodiment, the binding affinity of an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can have anassociation rate constant of, e.g., more than 1×10⁵ M⁻¹ s⁻¹, more than1×10⁶ M⁻¹ s⁻¹, more than 1×10⁷ M⁻¹ s⁻¹, or more than 1×10⁸ M⁻¹ s⁻¹. Inother aspects, the binding affinity of an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can have anassociation rate constant between 1×10⁵ M⁻¹ s⁻¹ to 1×10⁸ M⁻¹ s⁻¹, 1×10⁶M⁻¹ s⁻¹ to 1×10⁸ M⁻¹ s⁻¹, 1×10⁵ M⁻¹ s⁻¹ to 1×10⁷ M⁻¹ s⁻¹, or 1×10⁶ M⁻¹s⁻¹ to 1×10⁷ M⁻¹ s⁻¹.

In another embodiment, the binding affinity of an α-SNAP-25 antibodythat selectively binds to a SNAP-25 epitope having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond can have adisassociation rate constant of less than 1×10⁻³ s⁻¹, less than 1×10⁻⁴s⁻¹, or less than 1×10⁻⁵ s⁻¹. In other aspects of this embodiment, thebinding affinity of an α-SNAP-25 antibody that selectively binds to aSNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond can have a disassociation rateconstant of, e.g., less than 1.0×10⁻⁴ s⁻¹, less than 2.0×10⁻⁴ s⁻¹, lessthan 3.0×10⁻⁴ s⁻¹, less than 4.0×10⁻⁴ s⁻¹, less than 5.0×10⁻⁴ s⁻¹, lessthan 6.0×10⁻⁴ s⁻¹, less than 7.0×10⁻⁴ s⁻¹, less than 8.0×10⁻⁴ s⁻¹, orless than 9.0×10⁻⁴ s⁻¹. In another embodiment, the binding affinity ofan α-SNAP-25 antibody that selectively binds to a SNAP-25 epitope havinga carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond can have a disassociation rate constant of, e.g., morethan 1×10⁻³ s⁻¹, more than 1×10⁻⁴ s⁻¹, or more than 1×10⁻⁵ s⁻¹. In otheraspects of this embodiment, the binding affinity of an α-SNAP-25antibody that selectively binds to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond can have a disassociation rate constant of, e.g., more than1.0×10⁻⁴ s⁻¹, more than 2.0×10⁻⁴ s⁻¹, more than 3.0×10⁻⁴ s⁻¹, more than4.0×10⁻⁴ s⁻¹, more than 5.0×10⁻⁴ s⁻¹, more than 6.0×10⁻⁴ s⁻¹, more than7.0×10⁻⁴ s⁻¹, more than 8.0×10⁻⁴ s⁻¹, or more than 9.0×10⁻⁴ s⁻¹.

In another embodiment, the binding affinity of an α-SNAP-25 antibodythat selectively binds to a SNAP-25 epitope having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond can have anequilibrium disassociation constant of less than 0.500 nM. In aspects ofthis embodiment, the binding affinity of an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can have anequilibrium disassociation constant of, e.g., less than 0.500 nM, lessthan 0.450 nM, less than 0.400 nM, less than 0.350 nM, less than 0.300nM, less than 0.250 nM, less than 0.200 nM, less than 0.150 nM, lessthan 0.100 nM, or less than 0.050 nM. In another embodiment, the bindingaffinity of an α-SNAP-25 antibody that selectively binds to a SNAP-25epitope having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond can have an equilibrium disassociationconstant of more than 0.500 nM. In aspects of this embodiment, thebinding affinity of an α-SNAP-25 antibody that selectively binds to aSNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond can have an equilibriumdisassociation constant of, e.g., more than 0.500 nM, more than 0.450nM, more than 0.400 nM, more than 0.350 nM, more than 0.300 nM, morethan 0.250 nM, more than 0.200 nM, more than 0.150 nM, more than 0.100nM, or more than 0.050 nM.

In yet another embodiment, the binding affinity of an α-SNAP-25 antibodythat selectively binds to a SNAP-25 epitope having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond can have anassociation rate constant of for the intact SNAP-25 of, e.g., less than1×10⁰ M⁻¹ s⁻¹, less than 1×10¹ M⁻¹ s⁻¹, less than 1×10² M⁻¹ s⁻¹, lessthan 1×10³ M⁻¹ s⁻¹, or less than 1×10⁴ M⁻¹ s⁻¹. In another embodiment,the binding affinity of an α-SNAP-25 antibody that selectively binds toa SNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond can have an association rate constantof for the intact SNAP-25 of, e.g., at most 1×10⁰ M⁻¹ s⁻¹, at most 1×10¹M⁻¹ s⁻¹, at most 1×10² M⁻¹ s⁻¹ at most 1×10³ M⁻¹ s⁻¹, or at most 1×10⁴M⁻¹ s⁻¹.

Binding specificity is the ability of an antibody to discriminatebetween a molecule containing its epitope and a molecule that does notcontain that epitope. One way to measure binding specificity is tocompare the Kon association rate of the antibody for a moleculecontaining its epitope relative to the Kon association rate of theantibody for a molecule that does not contain that epitope. For example,comparing the association rate constant (Ka) of an α-SNAP-25 antibodyfor a SNAP-25 epitope having a carboxyl-terminus at the P₁ residue ofthe BoNT/A cleavage site scissile bond relative to a SNAP-25 notcomprising that epitope, such as, e.g., a SNAP-25 epitope lacking acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond or a SNAP-25 epitope having an intact P₁-P₁′ scissile bond of aBoNT/A cleavage site. In aspects of this embodiment, an α-SNAP-25antibody that selectively binds to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond has an association rate constant (Ka) for a SNAP-25 not comprisingits epitope(s) of, e.g., less than 1×10⁰ M⁻¹ s⁻¹, less than 1×10¹ M⁻¹s⁻¹, less than 1×10² M⁻¹ s⁻¹, less than 1×10³ M⁻¹ s⁻¹ or less than 1×10⁴M⁻¹ s⁻¹. In other aspects of this embodiment, an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond has an associationrate constant (Ka) for a SNAP-25 not comprising its epitope(s) of, e.g.,at most 1×10⁰ M⁻¹ s⁻¹, at most 1×10¹ M⁻¹ s⁻¹, at most 1×10² M⁻¹ s⁻¹, atmost 1×10³ M⁻¹ s⁻¹ or at most 1×10⁴ M⁻¹ s⁻¹.

In yet aspects of this embodiment, an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond has an associationrate constant (Ka) for its epitope relative to a SNAP-25 not comprisingthat epitope of, e.g., at least 2-fold more, at least 3-fold more, atleast 4-fold more, at least 5-fold more, at least 6-fold more, at least7-fold more, at least 8-fold more, or at least 9-fold more. In furtheraspects of this embodiment, an α-SNAP-25 antibody that selectively bindsto a SNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond has an association rate constant (Ka)for its epitope relative to a SNAP-25 not comprising that epitope of,e.g., at least 10-fold more, at least 100-fold more, at least 1,000-foldmore or at least 10,000-fold more. In yet other aspects of thisembodiment, an α-SNAP-25 antibody that selectively binds to a SNAP-25epitope having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond has an association rate constant (Ka) forits epitope relative to a SNAP-25 not comprising that epitope of, e.g.,at most 1-fold more, at most 2-fold more, at most 3-fold more, at most4-fold more, at most 5-fold more, at most 6-fold more, at most 7-foldmore, at most 8-fold more, or at most 9-fold more. In yet other aspectsof this embodiment, an α-SNAP-25 antibody that selectively binds to aSNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond has an association rate constant (Ka)for its epitope relative to a SNAP-25 not comprising that epitope of,e.g., at most 10-fold more, at most 100-fold more, at most 1,000-foldmore or at most 10,000-fold more.

The binding specificity of an α-SNAP-25 antibody that selectively bindsto a SNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond can also be characterized as a ratiothat such an α-SNAP-25 antibody can discriminate its SNAP-25 epitoperelative to a SNAP-25 not comprising that epitope, such as, e.g., aSNAP-25 epitope lacking a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond or a SNAP-25 epitope having an intactP₁-P₁′ scissile bond of a BoNT/A cleavage site. In aspects of thisembodiment, an α-SNAP-25 antibody that selectively binds to a SNAP-25epitope having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond has a binding specificity ratio for itsSNAP-25 epitope relative to a SNAP-25 not comprising that epitope of,e.g., at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least64:1, at least 7:1, at least 8:1, at least 9:1, at least 10:1, at least15:1, at least 20:1, at least 25:1, at least 30:1, at least 35:1, or atleast 40:1. In yet other aspects of this embodiment, an α-SNAP-25antibody that selectively binds to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond has a binding specificity ratio for its SNAP-25 epitope relative toa SNAP-25 lacking a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond of, e.g., at least 2:1, at least 3:1, atleast 4:1, at least 5:1, at least 6:1, at least 7:1, at least 8:1, atleast 9:1, at least 10:1, at least 15:1, at least 20:1, at least 25:1,at least 30:1, at least 35:1, or at least 40:1. In still other aspectsof this embodiment, an α-SNAP-25 antibody that selectively binds to aSNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond has a binding specificity ratio forits SNAP-25 epitope relative to a SNAP-25 having an intake P₁-P₁′scissile bond of a BoNT/A cleavage site of, e.g., at least 2:1, at least3:1, at least 4:1, at least 5:1, at least 64:1, at least 7:1, at least8:1, at least 9:1, at least 10:1, at least 15:1, at least 20:1, at least25:1, at least 30:1, at least 35:1, or at least 40:1.

Binding avidity, also known as functional affinity, refers to the sumtotal of the functional binding strength between a multivalent antibodyand its antigen. Antibody molecules can have more than one binding site(e.g., 2 for IgG, 10 for IgM), and many antigens contain more than oneantigenic site. While binding avidity of an antibody depends on thebinding affinities of the individual antibody binding sites, bindingavidity is greater than the binding affinity as all the antibody-antigeninteractions must be broken simultaneously for the antibody todissociate completely. It is envisioned that an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can selectivelybind to any and all epitopes for that antibody.

Thus, in an embodiment, an α-SNAP-25 antibody is an α-SNAP-25 antibodythat selectively binds to a SNAP-25 epitope having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond. In aspectsof this embodiment, an α-SNAP-25 antibody is an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminusglutamine or an α-SNAP-25 antibody that selectively binds to a SNAP-25epitope having a carboxyl-terminus lysine. In other aspects of thisembodiment, an α-SNAP-25 antibody is an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus P₁residue that corresponds to glutamine 197 of SEQ ID NO:5 or an α-SNAP-25antibody that selectively binds to a SNAP-25 epitope having acarboxyl-terminus P₁ residue that corresponds to lysine 204 of SEQ IDNO:16. In still other aspects of this embodiment, an α-SNAP-25 antibodyis an α-SNAP-25 antibody that selectively binds to a SNAP-25 epitopehaving a carboxyl-terminal amino acid sequence of SEQ ID NO:32, SEQ IDNO:33, SEQ ID NO:34, SEQ ID NO:35, SEQ ID NO:36, SEQ ID NO:37, SEQ IDNO:38, SEQ ID NO:39, SEQ ID NO:41, SEQ ID NO:42, SEQ ID NO:43, SEQ IDNO:44, SEQ ID NO:45, or SEQ ID NO:46.

Aspects of the present disclosure comprise, in part, an immuno-basedmethod of detecting retargeted endopeptidase activity. The immuno-basedmethods disclosed in the present specification can be evaluated byseveral parameters including, e.g., accuracy, precision, limit ofdetection (LOD), limits of quantitation (LOQ), range, specificity,selectivity, linearity, ruggedness, and system suitability. The accuracyof a method is the measure of exactness of an analytical method, or thecloseness of agreement between the measured value and the value that isaccepted as a conventional true value or an accepted reference value.The precision of a method is the degree of agreement among individualtest results, when the procedure is applied repeatedly to multiplesamplings of a homogeneous sample. As such, precision evaluates 1)within assay variability; 2) within-day variability (repeatability); and3) between-day variability (intermediate precision); and 4) between-labvariability (reproducibility). Coefficient of variation (CV %) is aquantitative measure of precision expressed relative to the observed ortheoretical mean value.

An immuno-based method disclosed in the present specification must beable to detect, over background, the presence of an α-SNAP-25antibody-antigen complex comprising a SNAP-25 having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond. The limitof detection (LOD) of a method refers to the concentration of analytewhich gives rise to a signal that is significantly different from thenegative control or blank and represents the lowest concentration ofanalyte that can be distinguished from background.

Thus, in an embodiment, the immuno-based method disclosed in the presentspecification can detect the LOD of retargeted endopeptidase at anamount that is significantly different from a negative control or blank.In aspect of this embodiment, the immuno-based method disclosed in thepresent specification has an LOD of, e.g., 10 ng or less, 9 ng or less,8 ng or less, 7 ng or less, 6 ng or less, 5 ng or less, 4 ng or less, 3ng or less, 2 ng or less, 1 ng or less of a retargeted endopeptidase. Instill other aspects of this embodiment, the immuno-based methoddisclosed in the present specification has an LOD of, e.g., 900 pg orless, 800 pg or less, 700 pg or less, 600 pg or less, 500 pg or less,400 pg or less, 300 pg or less, 200 pg or less, 100 pg or less of aretargeted endopeptidase. In further aspects of this embodiment, theimmuno-based method disclosed in the present specification has an LODof, e.g., 90 pg or less, 80 pg or less, 70 pg or less, 60 pg or less, 50pg or less, 40 pg or less, 30 pg or less, 20 pg or less, 10 pg or lessof a retargeted endopeptidase. In other aspects of this embodiment, theimmuno-based method disclosed in the present specification has an LODof, e.g., 9 pg or less, 8 pg or less, 7 pg or less, 6 pg or less, 5 pgor less, 4 pg or less, 3 pg or less, 2 pg or less, 1 pg or less of aretargeted endopeptidase. In yet other aspects of this embodiment, theimmuno-based method disclosed in the present specification has an LODof, e.g., 0.9 pg or less, 0.8 pg or less, 0.7 pg or less, 0.6 pg orless, 0.5 pg or less, 0.4 pg or less, 0.3 pg or less, 0.2 pg or less,0.1 pg or less of a retargeted endopeptidase.

In another aspect of this embodiment, the immuno-based method disclosedin the present specification has an LOD of, e.g., 100 nM or less orless, 90 nM or less or less, 80 nM or less or less, 70 nM or less orless, 60 nM or less or less, 50 nM or less or less, 40 nM or less orless, 30 nM or less or less, 20 nM or less or less, 10 nM or less orless, 9 nM or less, 8 nM or less, 7 nM or less, 6 nM or less, 5 nM orless, 4 nM or less, 3 nM or less, 2 nM or less, or 1 nM or less of aretargeted endopeptidase. In other aspects of this embodiment, theimmuno-based method disclosed in the present specification has an LODof, e.g., 900 pM or less, 800 pM or less, 700 pM or less, 600 pM orless, 500 pM or less, 400 pM or less, 300 pM or less, 200 pM or less, or100 pM or less of a retargeted endopeptidase. In other aspects of thisembodiment, the immuno-based method disclosed in the presentspecification has an LOD of, e.g., 100 pM or less, 90 pM or less, 80 pMor less, 70 pM or less, 60 pM or less, 50 pM or less, 40 pM or less, 30pM or less, 20 pM or less, or 10 pM or less of a retargetedendopeptidase. In yet other aspects of this embodiment, the immuno-basedmethod disclosed in the present specification has an LOD of, e.g., 10 pMor less of a retargeted endopeptidase, 9 pM or less, 8 pM or less, 7 pMor less, 6 pM or less, 5 pM or less, 4 pM or less, 3 pM or less, 2 pM orless, or 1 pM or less of a retargeted endopeptidase.

The limits of quantitation (LOQ) are the lowest and the highestconcentrations of analyte in a sample or specimen that can be measuredwith an acceptable level of accuracy and precision. The lower limit ofquantitation refers to the lowest dose that a detection method canmeasure consistently from the background. The upper limit ofquantitation is the highest dose that a detection method can measureconsistently before saturation of the signal occurs. The linear range ofthe method is the area between the lower and the upper limits ofquantitation. The linear range is calculated by subtracting lower limitof quantitation from the upper limit of quantitation. As used herein,the term “signal to noise ratio for the lower asymptote” refers to thesignal detected in the method at the lower limit of detection divided bythe background signal. As used herein, the term “signal to noise ratiofor the upper asymptote” refers to the signal detected in the method atthe upper limit of detection divided by the background signal.

Thus, in an embodiment, the immuno-based method disclosed in the presentspecification can detect the LOQ of retargeted endopeptidase at anamount that is significantly different from a negative control or blank.In aspect of this embodiment, the immuno-based method disclosed in thepresent specification has an LOQ of, e.g., 10 ng or less, 9 ng or less,8 ng or less, 7 ng or less, 6 ng or less, 5 ng or less, 4 ng or less, 3ng or less, 2 ng or less, 1 ng or less of a retargeted endopeptidase. Instill other aspects of this embodiment, the immuno-based methoddisclosed in the present specification has an LOQ of, e.g., 900 pg orless, 800 pg or less, 700 pg or less, 600 pg or less, 500 pg or less,400 pg or less, 300 pg or less, 200 pg or less, 100 pg or less of aretargeted endopeptidase. In further aspects of this embodiment, theimmuno-based method disclosed in the present specification has an LOQof, e.g., 90 pg or less, 80 pg or less, 70 pg or less, 60 pg or less, 50pg or less, 40 pg or less, 30 pg or less, 20 pg or less, 10 pg or lessof a retargeted endopeptidase. In other aspects of this embodiment, theimmuno-based method disclosed in the present specification has an LOQof, e.g., 9 pg or less, 8 pg or less, 7 pg or less, 6 pg or less, 5 pgor less, 4 pg or less, 3 pg or less, 2 pg or less, 1 pg or less of aretargeted endopeptidase. In yet other aspects of this embodiment, theimmuno-based method disclosed in the present specification has an LOQof, e.g., 0.9 pg or less, 0.8 pg or less, 0.7 pg or less, 0.6 pg orless, 0.5 pg or less, 0.4 pg or less, 0.3 pg or less, 0.2 pg or less,0.1 pg or less of a retargeted endopeptidase.

In another aspect of this embodiment, the immuno-based method disclosedin the present specification has an LOQ of, e.g., 100 nM or less orless, 90 nM or less or less, 80 nM or less or less, 70 nM or less orless, 60 nM or less or less, 50 nM or less or less, 40 nM or less orless, 30 nM or less or less, 20 nM or less or less, 10 nM or less orless, 9 nM or less, 8 nM or less, 7 nM or less, 6 nM or less, 5 nM orless, 4 nM or less, 3 nM or less, 2 nM or less, or 1 nM or less of aretargeted endopeptidase. In other aspects of this embodiment, theimmuno-based method disclosed in the present specification has an LOQof, e.g., 900 pM or less, 800 pM or less, 700 pM or less, 600 pM orless, 500 pM or less, 400 pM or less, 300 pM or less, 200 pM or less, or100 pM or less of a retargeted endopeptidase. In other aspects of thisembodiment, the immuno-based method disclosed in the presentspecification has an LOQ of, e.g., 100 pM or less, 90 pM or less, 80 pMor less, 70 pM or less, 60 pM or less, 50 pM or less, 40 pM or less, 30pM or less, 20 pM or less, or 10 pM or less of a retargetedendopeptidase. In yet other aspects of this embodiment, the immuno-basedmethod disclosed in the present specification has an LOQ of, e.g., 10 pMor less of a retargeted endopeptidase, 9 pM or less, 8 pM or less, 7 pMor less, 6 pM or less, 5 pM or less, 4 pM or less, 3 pM or less, 2 pM orless, or 1 pM or less of a retargeted endopeptidase.

An immuno-based assay useful to practice aspect of the disclosed methodsmust have a precision of no more than 50%. In aspects of thisembodiment, an immuno-based assay has a precision of no more than 50%,no more than 40%, no more than 30%, or no more than 20%. In otheraspects of this embodiment, an immuno-based assay has a precision of normore than 15%, no more than 10%, or no more than 5%. In other aspects ofthis embodiment, an immuno-based assay has a precision of nor more than4%, no more than 3%, no more than 2%, or no more than 1%.

An immuno-based assay useful to practice aspect of the disclosed methodsmust have an accuracy of at least 50%. In aspects of this embodiment, animmuno-based assay has an accuracy of at least 50%, at least 60%, atleast 70%, or at least 80%. In other aspects of this embodiment, animmuno-based assay has an accuracy of at least 85%, at least 90%, or atleast 95%. In other aspects of this embodiment, an immuno-based assayhas an accuracy of at least 96%, at least 97%, at least 98%, or at least99%.

An immuno-based method disclosed in the present specification must havea signal to noise ratio for the lower asymptote that is statisticallysignificant and a signal to noise ratio for the upper asymptote that isstatistically significant. In aspects of this embodiment, animmuno-based method disclosed in the present specification has a signalto noise ratio for the lower asymptote of, e.g., at least 3:1, at least4:1, at least 5:1, at least 6:1, at least 7:1, at least 8:1, at least9:1, at least 10:1, at least 15:1 or at least 20:1. In other aspects ofthis embodiment, an immuno-based method has a signal to noise ratio forthe upper asymptote of, e.g., at least 10:1, at least 15:1, at least20:1, at least 25:1, at least 30:1, at least 35:1, at least 40:1, atleast 45:1, at least 50:1, at least 60:1, at least 70:1, at least 80:1,at least 90:1, or at least 100:1, at least 150:1, at least 200:1, atleast 250:1, at least 300:1, at least 350:1, at least 400:1, at least450:1, at least 500:1, at least 550:1, or at least 600:1.

The specificity of a method defines the ability of the method to measurethe analyte of interest to the exclusion of other relevant components,such as, e.g., partially-active or inactive analyte. The selectivity ofa method describes the ability of an analytical method to differentiatevarious substances in a sample. The linearity of a method is its abilityto elicit results that are directly, or by a well defined mathematicaltransformation, proportional to the concentration of analyte in thesample. Thus in an embodiment, an immuno-based method disclosed in thepresent specification can distinguish a fully-active retargetedendopeptidase from a partially-active retargeted endopeptidase having,e.g., 70% or less, 60% or less, 50% or less, 40% or less, 30% or less,20% or less, or 10% or less the activity of a fully-active retargetedendopeptidase.

The ruggedness of the method is the reproducibility of the test resultsobtained for identical samples under normal (but variable) testconditions. Robustness of a procedure is a measure of its capacity toremain unaffected by small but deliberate variations in the methodparameters and provides an indication of its reliability in normalusage. Thus, whereas ruggedness evaluates unavoidable changes,robustness evaluates deliberate changes. Typical parameters evaluated byruggedness and robustness include the effects of freeze/thaw, incubationtimes, incubation temperature, longevity of reagent, sample preparation,sample storage, cell passage number, lots of re-targeted endopeptidase,variability between purifications, and variability between nickingreactions. Robustness parameters for cell-based assays include the cellbank (beginning, middle and end of freeze), cell passage level, cellseeding density, cell stock density (how many days in culture), cell agein flask (waiting time to seeding), incubation time, different plates,excessive amounts of serum, and source of reagents. The systemsuitability of the method is the determination of assay performance,including the performance of reagents and instruments, over time byanalysis of a reference standard or reference molecule. Systemsuitability is stressed in FDA guidance referring to the fact thatequipment, electronics, assay performance, and samples to be analyzed,constitute an integrated system. System suitability can be evaluated bytesting for parallelism, which is when plotting the log dose versus theresponse, serial dilutions of the reference and serial dilutions of thesamples should give rise to parallel curves.

Aspects of the present disclosure comprise, in part, a cell from anestablished cell line. As used herein, the term “cell” refers to anyeukaryotic cell susceptible to retargeted endopeptidase activity by aretargeted endopeptidase or any eukaryotic cell that can uptake aretargeted endopeptidase. The term cell encompasses cells from a varietyof organisms, such as, e.g., murine, rat, porcine, bovine, equine,primate and human cells; from a variety of cell types such as, e.g.,neuronal and non-neuronal; and can be isolated from or part of aheterogeneous cell population, tissue or organism. As used herein, theterm “established cell line” is synonymous with “immortal cell line,” or“transformed cell line” and refers to a cell culture of cells selectedfor indefinite propagation from a cell population derived from anorganism, tissue, or organ source. By definition, an established cellline excludes a cell culture of primary cells. As used herein, the term“primary cells” are cells harvested directly from fresh tissues ororgans and do not have the potential to propagate indefinitely. Anestablished cell line can comprise a heterogeneous population of cellsor a uniform population of cells. An established cell line derived froma single cell is referred to as a clonal cell line. An established cellline can be one whose cells endogenously express all component necessaryfor the cells to undergo the overall cellular mechanism whereby aretargeted endopeptidase proteolytically cleaves a SNAP-25 substrate andencompasses the binding of a retargeted endopeptidase to its receptor,the internalization of the endopeptidase/receptor complex, thetranslocation of the retargeted endopeptidase light chain from anintracellular vesicle into the cytoplasm and the proteolytic cleavage ofa SNAP-25. Alternatively, an established cell line can be one whosecells have had introduced from an exogenous source at least onecomponent necessary for the cells to undergo the overall cellularmechanism whereby a retargeted endopeptidase proteolytically cleaves aSNAP-25 substrate and encompasses the binding of a retargetedendopeptidase to its receptor, the internalization of theendopeptidase/receptor complex, the translocation of the retargetedendopeptidase light chain from an intracellular vesicle into thecytoplasm and the proteolytic cleavage of a SNAP-25. Also referred to asa genetically-engineered cell line, cells from such an established cellline may, e.g., express an exogenous retargeted endopeptidase, such as,e.g., an exogenous ORL1, an exogenous DOR, an exogenous KOR, anexogenous MOR, an exogenous Galanin receptor 1, an exogenous Galaninreceptor 2, an exogenous Galanin receptor 3, or any combination thereof.

Aspects of the present disclosure comprise, in part, a cell from anestablished cell line susceptible to retargeted endopeptidase activity.As used herein, the terms “cell(s) susceptible to retargetedendopeptidase activity,” “cell(s) susceptible to retargetedendopeptidase activity by a retargeted endopeptidase,” or “cell(s) froman established cell line susceptible to retargeted endopeptidaseactivity by a retargeted endopeptidase” refer to cell(s) that canundergo the overall cellular mechanism whereby a retargetedendopeptidase proteolytically cleaves a SNAP-25 substrate therebyinhibiting exocytosis and encompasses the binding of a retargetedendopeptidase to its receptor, the internalization of theendopeptidase/receptor complex, the translocation of the retargetedendopeptidase activity chain from an intracellular vesicle into thecytoplasm and the proteolytic cleavage of a SNAP-25. By definition,cell(s) susceptible to retargeted endopeptidase activity must express,or be engineered to express, at least one retargeted endopeptidasereceptor and at least one SNAP-25 substrate. As used herein, the terms“cell(s) that can uptake retargeted endopeptidase” or “cell(s)comprising an established cell line that can uptake retargetedendopeptidase” refer to cells that can undergo the overall cellularmechanism whereby a retargeted endopeptidase proteolytically cleaves aSNAP-25 substrate thereby inhibiting exocytosis and encompasses thebinding of a retargeted endopeptidase to its receptor, theinternalization of the endopeptidase/receptor complex, the translocationof the retargeted endopeptidase light chain from an intracellularvesicle into the cytoplasm and the proteolytic cleavage of a SNAP-25. Bydefinition, cell(s) that can uptake retargeted endopeptidase mustexpress, or be engineered to express, at least one retargetedendopeptidase receptor and at least one SNAP-25 substrate.

Thus in an embodiment, cells from an established cell line aresusceptible to retargeted endopeptidase activity. In aspects of thisembodiment, cells from an established cell line are susceptible toretargeted endopeptidase activity by, e.g., about 100 nM or less orless, about 90 nM or less or less, about 80 nM or less or less, about 70nM or less or less, about 60 nM or less or less, about 50 nM or less orless, about 40 nM or less or less, about 30 nM or less or less, about 20nM or less or less, about 10 nM or less or less of a retargetedendopeptidase. In other aspects, cells from an established cell line aresusceptible to retargeted endopeptidase activity by, e.g., about 9 nM orless, about 8 nM or less, about 7 nM or less, about 6 nM or less, about5 nM or less, about 4 nM or less, about 3 nM or less, about 2 nM orless, or about 1 nM or less of a retargeted endopeptidase. In yet otheraspects, cells from an established cell line are susceptible toretargeted endopeptidase activity by, e.g., about 0.9 nM or less, about0.8 nM or less, about 0.7 nM or less, about 0.6 nM or less, about 0.5 nMor less, about 0.4 nM or less, about 0.3 nM or less, about 0.2 nM, orabout 0.1 nM or less of a retargeted endopeptidase. As used herein, theterm “about” when qualifying a value of a stated item, number,percentage, or term refers to a range of plus or minus ten percent ofthe value of the stated item, percentage, parameter, or term.

In another embodiment, cells comprising an established cell line canuptake a retargeted endopeptidase. In aspects of this embodiment, cellscomprising an established cell line can uptake, e.g., about 100 nM orless or less, about 90 nM or less or less, about 80 nM or less or less,about 70 nM or less or less, about 60 nM or less or less, about 50 nM orless or less, about 40 nM or less or less, about 30 nM or less or less,about 20 nM or less or less, about 10 nM or less or less of a retargetedendopeptidase. In other aspects, cells comprising an established cellline possess the ability to uptake about 9 nM or less, about 8 nM orless, about 7 nM or less, about 6 nM or less, about 5 nM or less, about4 nM or less, about 3 nM or less, about 2 nM or less, or about 1 nM orless of a retargeted endopeptidase. In yet other aspects, cellscomprising an established cell line possess the ability to uptake about0.9 nM or less, about 0.8 nM or less, about 0.7 nM or less, about 0.6 nMor less, about 0.5 nM or less, about 0.4 nM or less, about 0.3 nM orless, about 0.2 nM or less, or about 0.1 nM or less of a retargetedendopeptidase.

Aspects of the present disclosure comprise, in part, cells from anestablished cell line that exhibit a selective binding for a retargetedendopeptidase disclosed in the present specification. As used herein,the term “selectively binds”, or “selective binding” when made inreference to a retargeted endopeptidase, refers to the discriminatorybinding of a retargeted endopeptidase to the indicated target receptorsuch that the retargeted endopeptidase does not substantially bind to anon-target receptor. The degree to which cells from an established cellline exhibit selectively binding for a retargeted endopeptidase can bemeasured by the extent these cells exhibit non-selective uptake for amolecule lacking the targeting domain of the retargeted endopeptidase.One way to assess non-selective uptake for a molecule lacking thetargeting domain of the retargeted endopeptidase is to measure thenon-selective uptake of a LH_(N) fragment. An LH_(N) fragment is onethat comprises a Clostridial toxin translocation domain and aClostridial toxin enzymatic domain, but lacks any targeting domainaltogether. Non-limiting examples of a LH_(N) fragments include aLH_(N)/A fragment, a LH_(N)/B fragment, a LH_(N)/C fragment, a LH_(N)/Dfragment, a LH_(N)/E fragment, a LH_(N)/F fragment, and a LH_(N)/Gfragment. An exemplary LH_(N)/A fragment is SEQ ID NO:146 which isencoded by the polynucleotide molecule SEQ ID NO:147.

Thus, in an embodiment, cells from an established cell line exhibitselective binding for a retargeted endopeptidase. In aspects of thisembodiment, cells from an established cell line exhibit selectivebinding for a retargeted endopeptidase that represents, e.g., at least75% of the total activity assayed, at least 80% of the total activityassayed, at least 85% of the total activity assayed, at least 90% of thetotal activity assayed, or at least 95% of the total activity assayed.In other aspects of this embodiment, cells from an established cell lineexhibit selective binding for a retargeted endopeptidase thatrepresents, e.g., about 75% to about 100% of the total activity assayed,about 80% to about 100% of the total activity assayed, about 85% toabout 100% of the total activity assayed, about 90% to about 100% of thetotal activity assayed.

In another embodiment, cells from an established cell line exhibitminimal non-selective uptake of a LH_(N) fragment. In aspects of thisembodiment, cells from an established cell line exhibit non-selectiveuptake of a LH_(N) fragment that is, e.g., at most 25% of the totaluptake measured, at most 20% of the total uptake measured, at most 15%of the total uptake measured, at most 10% of the total uptake measured,or at most 5% of the total uptake measured. In other aspects of thisembodiment, cells from an established cell line exhibit non-selectiveuptake of a LH_(N) fragment that is, e.g., about 0% to about 25% of thetotal uptake measured, about 0% to about 20% of the total uptakemeasured, about 0% to about 15% of the total uptake measured, about 0%to about 10% of the total uptake measured, or about 0% to about 5% ofthe total uptake measured.

In yet another embodiment, cells from an established cell line exhibitminimal non-selective uptake of a LH_(N)/A fragment. In aspects of thisembodiment, cells from an established cell line exhibit non-selectiveuptake of a LH_(N)/A fragment that is, e.g., at most 25% of the totaluptake measured, at most 20% of the total uptake measured, at most 15%of the total uptake measured, at most 10% of the total uptake measured,or at most 5% of the total uptake measured. In other aspects of thisembodiment, cells from an established cell line exhibit non-selectiveuptake of a LH_(N)/A fragment that is, e.g., about 0% to about 25% ofthe total uptake measured, about 0% to about 20% of the total uptakemeasured, about 0% to about 15% of the total uptake measured, about 0%to about 10% of the total uptake measured, or about 0% to about 5% ofthe total uptake measured.

Aspects of the present disclosure comprise, in part, cells from anestablished cell line that exhibit a sufficient number of receptorbinding sites on the plasma membrane to confer sensitive and selectivebinding for a retargeted endopeptidase. An equilibrium saturationbinding assay measures the total and non-specific binding of a ligand atvarious concentrations. The equilibrium dissociation constant (K_(d))for the ligand and the maximal number of receptor binding sites, Bmax,can be calculated from the specific binding using non-linear regressionanalysis. Specific binding is calculated by subtracting the non-specificbinding of a ligand from the total binding observed. K_(d) is theconcentration of ligand required to reach half-maximal binding and ismeasured in terms of molarity. Bmax is the maximal number of bindingsites present on the plasma membrane and is measured in terms ofpmol/mg, pmol/cell, fmol/cell, or sites/cell.

Thus, in an embodiment, cells from an established cell line exhibit asufficient number of receptor binding sites on the plasma membrane toconfer sensitive and selective binding for a retargeted endopeptidase.In aspects of this embodiment, cells from an established cell lineexhibit a Bmax value of, e.g., at least 0.1 fmol/cell, at least 0.2fmol/cell, at least 0.3 fmol/cell, at least 0.4 fmol/cell, at least 0.5fmol/cell, at least 0.6 fmol/cell, at least 0.7 fmol/cell, at least 0.8fmol/cell, at least 0.9 fmol/cell, or at least 1.0 fmol/cell, for thetargeting ligand of a retargeted endopeptidase. In other aspects of thisembodiment, cells from an established cell line exhibit a Bmax value of,e.g., at least 1 fmol/cell, at least 2 fmol/cell, at least 3 fmol/cell,at least 4 fmol/cell, at least 5 fmol/cell, at least 6 fmol/cell, atleast 7 fmol/cell, at least 8 fmol/cell, at least 9 fmol/cell, or atleast 10 fmol/cell, for the targeting ligand of a retargetedendopeptidase.

Aspects of the present disclosure comprise, in part, cells from anestablished clonal cell line susceptible to re-targeted endopeptidaseactivity that are more stable than cells from the parental cell linefrom which the clonal cell line was derived. As used herein, the term“stable” refers to cells from an established clonal cell line for aparticular passage number that exhibit a relative EC₅₀, sensitivity,efficacy, well-defined upper asymptote, and/or a well-defineddose-response curve for re-targeted endopeptidase activity that issimilar to the values for relative EC₅₀, sensitivity, efficacy,well-defined upper asymptote, and/or a well-defined dose-response curveexhibited by cells from the parental cell line from which the clonalcell line was derived, at the same or similar passage number, where thesame assay conditions and the same re-targeted endopeptidase are used inboth assays.

Thus in an embodiment, cells from an established clonal cell line aremore stable as compared to from the parental cell line from which theclonal cell line was derived. In an aspect of this embodiment, cellsfrom an established clonal cell line are more stable as compared to theparental SK-N-DZ cell line. In another aspect of this embodiment, cellsfrom an established clonal cell line are more stable as compared to theparental SK-N-DZ cell line ATCC CRL-2149. In other aspects of thisembodiment, cells from an established clonal cell line are more stablefor, e.g., at least 5 more passages, at least 10 more passages, at least15 more passages, at least 20 more passages, at least 25 more passages,or at least 30 more passages, as compared to from the parental cell linefrom which the clonal cell line was derived. In yet other aspects ofthis embodiment, cells from an established clonal cell line are morestable for, e.g., at least 5 more passages, at least 10 more passages,at least 15 more passages, at least 20 more passages, at least 25 morepassages, or at least 30 more passages, as compared to from the parentalcell line from which the clonal cell line was derived.

Aspects of the present disclosure comprise, in part, cells from anestablished clonal cell line susceptible to re-targeted endopeptidaseactivity that are stable over a plurality of cell passages. As usedherein, the term “stable” refers to cells from an established clonalcell line for a particular passage number that exhibit a relative EC₅₀,sensitivity, efficacy, well-defined upper asymptote, and/or awell-defined dose-response curve for re-targeted endopeptidase activitythat is similar to the values for relative EC₅₀, sensitivity, efficacy,well-defined upper asymptote, and/or a well-defined dose-response curveexhibited by cells from the same established clonal cell line, but froma prior passage or passages, where the same assay conditions and thesame re-targeted endopeptidase are used in both assays.

Cells from an established cell line disclosed in the presentspecification can exhibit a consistent sensitivity for re-targetedendopeptidase activity over a plurality of cell passages. As usedherein, the term “sensitivity for re-targeted endopeptidase activity”refers to the lowest dose that an assay can measure consistently abovethe signal detected by a non-treatment control or background signal.

Thus, in an embodiment, cells from the established clonal cell lineexhibit a sensitivity for re-targeted endopeptidase activity for anygiven passages that is e.g., 100 nM or less, about 80 nM or less, about70 nM or less, about 60 nM or less, about 50 nM or less, about 40 nM orless, about 30 nM or less, about 20 nM or less, about 10 nM or less,about 1 nM or less, about 0.9 nM or less, about 0.8 nM or less, about0.7 nM or less, about 0.6 nM or less, about 0.5 nM or less, about 0.4 nMor less, about 0.3 nM or less, about 0.2 nM or less, or about 0.1 nM orless of a re-targeted endopeptidase. In aspects of this embodiment,cells from the established clonal cell line exhibit a sensitivity forre-targeted endopeptidase activity for any given passages that is, e.g.,about 0.01 nM to about 100 nM, about 0.01 nM to about 75 nM, about 0.01nM to about 50 nM, about 0.01 nM to about 25 nM, about 0.01 nM to about20 nM, about 0.01 nM to about 15 nM, about 0.01 nM to about 10 nM, about0.01 nM to about 5 nM, about 0.001 nM to about 100 nM, about 0.001 nM toabout 75 nM, about 0.001 nM to about 50 nM, about 0.001 nM to about 25nM, about 0.001 nM to about 20 nM, about 0.001 nM to about 15 nM, about0.001 nM to about 10 nM, or about 0.001 nM to about 5 nM of are-targeted endopeptidase.

In another embodiment, cells from the established clonal cell lineexhibit a sensitivity for re-targeted endopeptidase activity that isabout 100 nM or less, about 75 nM or less, about 50 nM or less, about 25nM or less, less about 20 nM or less, about 15 nM or less, about 10 nMor less, or about 1 nM or less for, e.g., 5 or more cell passages, 10 ormore cell passages, 15 or more cell passages, 20 or more cell passages,25 or more cell passages, 30 or more cell passages, 35 or more cellpassages, 40 or more cell passages, 45 or more cell passages, or 50 ormore cell passages. In other aspects of this embodiment, cells from theestablished clonal cell line exhibit a sensitivity for re-targetedendopeptidase activity that is about 100 nM or less, about 75 nM orless, about 50 nM or less, about 25 nM or less, less about 20 nM orless, about 15 nM or less, about 10 nM or less, or about 1 nM or lessfor, e.g., about 15 to about 60 passages, about 20 to about 60 passages,about 25 to about 60 passages, about 30 to about 60 passages, about 35to about 60 passages, about 40 to about 60 passages, about 45 to about60 passages, about 50 to about 60 passages, about 15 to about 50passages, about 20 to about 50 passages, about 25 to about 50 passages,about 30 to about 50 passages, about 35 to about 50 passages, about 40to about 50 passages, about 15 to about 40 passages, about 20 to about40 passages, about 25 to about 40 passages, or about 30 to about 40passages.

Cells from an established cell line disclosed in the presentspecification can exhibit a consistent relative efficacy of re-targetedendopeptidase uptake or re-targeted endopeptidase activity over aplurality of cell passages. As used herein, the term “relative efficacy”refers to how well the upper asymptote for the re-targeted endopeptidaseactivity detected in the current assay run compares to the upperasymptote for the re-targeted endopeptidase activity detected in areference standard, a reference molecule, or a reference passage numberused on that assay. As used herein, the term “signal to noise ratio forthe upper asymptote” refers to the signal detected in an assay at theupper limit of detection divided by the signal detected by anon-treatment control or background signal. The upper limit of detectionis the highest dose that an assay can measure consistently beforesaturation of the signal occurs.

Thus, in an embodiment, cells from an established cell line disclosed inthe present specification can exhibit a well defined upper asymptoteover a plurality of cell passages and maintain a signal to noise ratiothat is consistent and adequate for the assay. In aspects of thisembodiment, cells from an established cell line disclosed in the presentspecification must have a well defined signal to noise ratio for theupper asymptote for re-targeted endopeptidase activity of, e.g., atleast 3:1, at least 4:1, at least 5:1, at least 6:1, at least 7:1, atleast 8:1, at least 9:1, at least 10:1, at least 15:1, at least 20:1, atleast 25:1, at least 30:1, at least 35:1, at least 40:1, at least 45:1,at least 50:1, at least 60:1, at least 70:1, at least 80:1, at least90:1, or at least 100:1, at least 150:1, at least 200:1, at least 250:1,at least 300:1, at least 350:1, at least 400:1, at least 450:1, at least500:1, at least 550:1, or at least 600:1, over, e.g., 5 or more cellpassages, 10 or more cell passages, 15 or more cell passages, 20 or morecell passages, 25 or more cell passages, 30 or more cell passages, 35 ormore cell passages, 40 or more cell passages, 45 or more cell passages,or 50 or more cell passages. In other aspects of this embodiment, cellsfrom an established cell line disclosed in the present specificationmust have a well defined signal to noise ratio for the upper asymptotefor re-targeted endopeptidase activity of, e.g., at least 3:1, at least4:1, at least 5:1, at least 6:1, at least 7:1, at least 8:1, at least9:1, at least 10:1, at least 15:1, at least 20:1, at least 25:1, atleast 30:1, at least 35:1, at least 40:1, at least 45:1, at least 50:1,at least 60:1, at least 70:1, at least 80:1, at least 90:1, or at least100:1, at least 150:1, at least 200:1, at least 250:1, at least 300:1,at least 350:1, at least 400:1, at least 450:1, at least 500:1, at least550:1, or at least 600:1, over, e.g., about 15 to about 60 passages,about 20 to about 60 passages, about 25 to about 60 passages, about 30to about 60 passages, about 35 to about 60 passages, about 40 to about60 passages, about 45 to about 60 passages, about 50 to about 60passages, about 15 to about 50 passages, about 20 to about 50 passages,about 25 to about 50 passages, about 30 to about 50 passages, about 35to about 50 passages, about 40 to about 50 passages, about 15 to about40 passages, about 20 to about 40 passages, about 25 to about 40passages, or about 30 to about 40 passages.

Cells from an established cell line disclosed in the presentspecification can exhibit a well defined dose-response curve forre-targeted endopeptidase activity over a plurality of cell passages. Asused herein, the term “dose-response curve” refers to the how well theraw data fits the statistical model of choice for that assay. As anon-limiting example, a sigmoidal curve with a four parameter logisticsfit is a dose-response curve for an enzymatic activity assay, such as,e.g. a potency assay. As another non-limiting example, a ligand bindingwith one site saturation fit is a dose-response curve for aligand/antibody binding assay.

Thus, in an embodiment, cells from an established cell line disclosed inthe present specification exhibit a well defined dose-response curve forre-targeted endopeptidase activity over a plurality of cell passages. Inaspects of this embodiment, cells from an established cell linedisclosed in the present specification exhibit a well defineddose-response curve for re-targeted endopeptidase activity over, e.g., 5or more cell passages, 10 or more cell passages, 15 or more cellpassages, 20 or more cell passages, 25 or more cell passages, 30 or morecell passages, 35 or more cell passages, 40 or more cell passages, 45 ormore cell passages, or 50 or more cell passages. In other aspects ofthis embodiment, cells from an established cell line disclosed in thepresent specification exhibit a well defined dose-response curve forre-targeted endopeptidase activity over, e.g., about 15 to about 60passages, about 20 to about 60 passages, about 25 to about 60 passages,about 30 to about 60 passages, about 35 to about 60 passages, about 40to about 60 passages, about 45 to about 60 passages, about 50 to about60 passages, about 15 to about 50 passages, about 20 to about 50passages, about 25 to about 50 passages, about 30 to about 50 passages,about 35 to about 50 passages, about 40 to about 50 passages, about 15to about 40 passages, about 20 to about 40 passages, about 25 to about40 passages, or about 30 to about 40 passages.

Cells from an established cell line disclosed in the presentspecification can exhibit a consistent relative EC₅₀ value forre-targeted endopeptidase activity over a plurality of cell passages. Asused herein, the term “relative EC₅₀” or “relative EC₅₀ value” refers toan EC₅₀ value for re-targeted endopeptidase activity that is normalizedagainst the EC₅₀ calculated for a reference standard, a referencemolecule, or a reference passage number used on that assay.

Thus, in an embodiment, cells from an established clonal cell lineexhibit a consistent relative EC₅₀ for re-targeted endopeptidaseactivity over a plurality of cell passages. In aspects of thisembodiment, cells from an established clonal cell line exhibit aconsistent relative EC₅₀ for re-targeted endopeptidase activity that is,e.g., about ±10%, about ±20%, about ±30%, about ±40%, about ±50%, about±60%, about ±70%, or about ±75% the relative EC₅₀ for re-targetedendopeptidase activity over, e.g., 5 or more cell passages, 10 or morecell passages, 15 or more cell passages, 20 or more cell passages, 25 ormore cell passages, 30 or more cell passages, 35 or more cell passages,40 or more cell passages, 45 or more cell passages, or 50 or more cellpassages. In other aspects of this embodiment, cells from an establishedclonal cell line exhibit a relative EC₅₀ for re-targeted endopeptidaseactivity that is, e.g., about ±10% to about 75%, about ±10% to about70%, about ±10% to about 60%, about ±10% to about 50%, about ±10% toabout 40%, about ±10% to about 30%, or about ±10% to about 20% therelative EC₅₀ for re-targeted endopeptidase activity over, e.g., 5 ormore cell passages, 10 or more cell passages, 15 or more cell passages,20 or more cell passages, 25 or more cell passages, 30 or more cellpassages, 35 or more cell passages, 40 or more cell passages, 45 or morecell passages, or 50 or more cell passages.

Aspects of the present disclosure comprise, in part, a retargetedendopeptidase. As used herein, the term “retargeted endopeptidase” issynonymous with “Targeted Vesicular Exocytosis Modulator Protein” or“TVEMP.” Non-limiting examples of retargeted endopeptidase are disclosedin, e.g., Keith A. Foster et al., Clostridial Toxin Derivatives Able ToModify Peripheral Sensory Afferent Functions, U.S. Pat. No. 5,989,545;Clifford C. Shone et al., Recombinant Toxin Fragments, U.S. Pat. No.6,461,617; Conrad P. Quinn et al., Methods and Compounds for theTreatment of Mucus Hypersecretion, U.S. Pat. No. 6,632,440; Lance E.Steward et al., Methods And Compositions For The Treatment OfPancreatitis, U.S. Pat. No. 6,843,998; Stephan Donovan, ClostridialToxin Derivatives and Methods For Treating Pain, U.S. Patent Publication2002/0037833; Keith A. Foster et al., Inhibition of Secretion fromNon-neural Cells, U.S. Patent Publication 2003/0180289; J. Oliver Dollyet al., Activatable Recombinant Neurotoxins, WO 2001/014570; Keith A.Foster et al., Re-targeted Toxin Conjugates, International PatentPublication WO 2005/023309; Lance E. Steward et al., MultivalentClostridial Toxin Derivatives and Methods of Their Use, U.S. patentapplication Ser. No. 11/376,696; Steward, L. E. et al., ModifiedClostridial Toxins with Enhanced Translocation Capabilities and AlteredTargeting Activity For Non-Clostridial Toxin Target Cells, U.S. patentapplication Ser. No. 11/776,075; Dolly, J. O. et al., ActivatableClostridial Toxins, U.S. patent application Ser. No. 11/829,475; Foster,K. A. et al., Fusion Proteins, International Patent Publication WO2006/059093; and Foster, K. A. et al., Non-Cytotoxic Protein Conjugates,International Patent Publication WO 2006/059105, each of which isincorporated by reference in its entirety. Non-limiting examples ofretargeted endopeptidases include SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3,SEQ ID NO:4, SEQ ID NO:130, and SEQ ID NO:131.

Thus in an embodiment, the retargeted endopeptidase activity beingdetected is from a retargeted endopeptidase. In aspects of thisembodiment, the retargeted endopeptidase activity being detected is froma retargeted endopeptidase disclosed in Keith A. Foster et al.,Clostridial Toxin Derivatives Able To Modify Peripheral Sensory AfferentFunctions, U.S. Pat. No. 5,989,545; Clifford C. Shone et al.,Recombinant Toxin Fragments, U.S. Pat. No. 6,461,617; Conrad P. Quinn etal., Methods and Compounds for the Treatment of Mucus Hypersecretion,U.S. Pat. No. 6,632,440; Lance E. Steward et al., Methods AndCompositions For The Treatment Of Pancreatitis, U.S. Pat. No. 6,843,998;Stephan Donovan, Clostridial Toxin Derivatives and Methods For TreatingPain, U.S. Patent Publication 2002/0037833; Keith A. Foster et al.,Inhibition of Secretion from Non-neural Cells, U.S. Patent Publication2003/0180289; J. Oliver Dolly et al., Activatable RecombinantNeurotoxins, WO 2001/014570; Keith A. Foster et al., Re-targeted ToxinConjugates, International Patent Publication WO 2005/023309; Lance E.Steward et al., Multivalent Clostridial Toxin Derivatives and Methods ofTheir Use, U.S. patent application Ser. No. 11/376,696; Steward, L. E.et al., Modified Clostridial Toxins with Enhanced TranslocationCapabilities and Altered Targeting Activity For Non-Clostridial ToxinTarget Cells, U.S. patent application Ser. No. 11/776,075; Dolly, J. O.et al., Activatable Clostridial Toxins, U.S. patent application Ser. No.11/829,475; Foster, K. A. et al., Fusion Proteins, International PatentPublication WO 2006/059093; and Foster, K. A. et al., Non-CytotoxicProtein Conjugates, International Patent Publication WO 2006/059105,each of which is incorporated by reference in its entirety. In aspectsof this embodiment, a retargeted endopeptidase is SEQ ID NO:1, SEQ IDNO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:130, or SEQ ID NO:131.

In another embodiment, the retargeted endopeptidase activity beingdetected is from a retargeted endopeptidase having, e.g., at least 70%,at least 75%, at least 80%, at least 85%, at least 90%, or at least 95%amino acid identity with a retargeted endopeptidase disclosed in KeithA. Foster et al., Clostridial Toxin Derivatives Able To ModifyPeripheral Sensory Afferent Functions, U.S. Pat. No. 5,989,545; CliffordC. Shone et al., Recombinant Toxin Fragments, U.S. Pat. No. 6,461,617;Conrad P. Quinn et al., Methods and Compounds for the Treatment of MucusHypersecretion, U.S. Pat. No. 6,632,440; Lance E. Steward et al.,Methods And Compositions For The Treatment Of Pancreatitis, U.S. Pat.No. 6,843,998; Stephan Donovan, Clostridial Toxin Derivatives andMethods For Treating Pain, U.S. Patent Publication 2002/0037833; KeithA. Foster et al., Inhibition of Secretion from Non-neural Cells, U.S.Patent Publication 2003/0180289; J. Oliver Dolly et al., ActivatableRecombinant Neurotoxins, WO 2001/014570; Keith A. Foster et al.,Re-targeted Toxin Conjugates, International Patent Publication WO2005/023309; Lance E. Steward et al., Multivalent Clostridial ToxinDerivatives and Methods of Their Use, U.S. patent application Ser. No.11/376,696; Steward, L. E. et al., Modified Clostridial Toxins withEnhanced Translocation Capabilities and Altered Targeting Activity ForNon-Clostridial Toxin Target Cells, U.S. patent application Ser. No.11/776,075; Dolly, J. O. et al., Activatable Clostridial Toxins, U.S.patent application Ser. No. 11/829,475; Foster, K. A. et al., FusionProteins, International Patent Publication WO 2006/059093; and Foster,K. A. et al., Non-Cytotoxic Protein Conjugates, International PatentPublication WO 2006/059105, each of which is incorporated by referencein its entirety. In another embodiment, the retargeted endopeptidaseactivity being detected is from a retargeted endopeptidase having, e.g.,at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, orat least 95% amino acid identity with a retargeted endopeptidase of SEQID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:130, or SEQ IDNO:131.

In other aspects of this embodiment, the retargeted endopeptidaseactivity being detected is from a re-targeted endopeptidase having,e.g., 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more,7 or more, 8 or more, 9 or more, 10 or more, 20 or more, 30 or more, 40or more, 50 or more, or 100 or more non-contiguous amino acidsubstitutions, deletions, or additions relative to a retargetedendopeptidase disclosed in Keith A. Foster et al., Clostridial ToxinDerivatives Able To Modify Peripheral Sensory Afferent Functions, U.S.Pat. No. 5,989,545; Clifford C. Shone et al., Recombinant ToxinFragments, U.S. Pat. No. 6,461,617; Conrad P. Quinn et al., Methods andCompounds for the Treatment of Mucus Hypersecretion, U.S. Pat. No.6,632,440; Lance E. Steward et al., Methods And Compositions For TheTreatment Of Pancreatitis, U.S. Pat. No. 6,843,998; Stephan Donovan,Clostridial Toxin Derivatives and Methods For Treating Pain, U.S. PatentPublication 2002/0037833; Keith A. Foster et al., Inhibition ofSecretion from Non-neural Cells, U.S. Patent Publication 2003/0180289;J. Oliver Dolly et al., Activatable Recombinant Neurotoxins, WO2001/014570; Keith A. Foster et al., Re-targeted Toxin Conjugates,International Patent Publication WO 2005/023309; Lance E. Steward etal., Multivalent Clostridial Toxin Derivatives and Methods of Their Use,U.S. patent application Ser. No. 11/376,696; Steward, L. E. et al.,Modified Clostridial Toxins with Enhanced Translocation Capabilities andAltered Targeting Activity For Non-Clostridial Toxin Target Cells, U.S.patent application Ser. No. 11/776,075; Dolly, J. O. et al., ActivatableClostridial Toxins, U.S. patent application Ser. No. 11/829,475; Foster,K. A. et al., Fusion Proteins, International Patent Publication WO2006/059093; and Foster, K. A. et al., Non-Cytotoxic Protein Conjugates,International Patent Publication WO 2006/059105, each of which isincorporated by reference in its entirety. In other aspects of thisembodiment, the retargeted endopeptidase activity being detected is froma re-targeted endopeptidase having, e.g., 1 or more, 2 or more, 3 ormore, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more,10 or more, 20 or more, 30 or more, 40 or more, 50 or more, or 100 ormore non-contiguous amino acid substitutions, deletions, or additionsrelative to a retargeted endopeptidase of SEQ ID NO:1, SEQ ID NO:2, SEQID NO:3, SEQ ID NO:4, SEQ ID NO:130, or SEQ ID NO:131.

In yet other aspects of this embodiment, the retargeted endopeptidaseactivity being detected is from a non-naturally occurring retargetedendopeptidase variant having, e.g., 1 or more, 2 or more, 3 or more, 4or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 ormore, 20 or more, 30 or more, 40 or more, 50 or more, or 100 or morecontiguous amino acid substitutions, deletions, or additions relative toa retargeted endopeptidase disclosed in Keith A. Foster et al.,Clostridial Toxin Derivatives Able To Modify Peripheral Sensory AfferentFunctions, U.S. Pat. No. 5,989,545; Clifford C. Shone et al.,Recombinant Toxin Fragments, U.S. Pat. No. 6,461,617; Conrad P. Quinn etal., Methods and Compounds for the Treatment of Mucus Hypersecretion,U.S. Pat. No. 6,632,440; Lance E. Steward et al., Methods AndCompositions For The Treatment Of Pancreatitis, U.S. Pat. No. 6,843,998;Stephan Donovan, Clostridial Toxin Derivatives and Methods For TreatingPain, U.S. Patent Publication 2002/0037833; Keith A. Foster et al.,Inhibition of Secretion from Non-neural Cells, U.S. Patent Publication2003/0180289; J. Oliver Dolly et al., Activatable RecombinantNeurotoxins, WO 2001/014570; Keith A. Foster et al., Re-targeted ToxinConjugates, International Patent Publication WO 2005/023309; Lance E.Steward et al., Multivalent Clostridial Toxin Derivatives and Methods ofTheir Use, U.S. patent application Ser. No. 11/376,696; Steward, L. E.et al., Modified Clostridial Toxins with Enhanced TranslocationCapabilities and Altered Targeting Activity For Non-Clostridial ToxinTarget Cells, U.S. patent application Ser. No. 11/776,075; Dolly, J. O.et al., Activatable Clostridial Toxins, U.S. patent application Ser. No.11/829,475; Foster, K. A. et al., Fusion Proteins, International PatentPublication WO 2006/059093; and Foster, K. A. et al., Non-CytotoxicProtein Conjugates, International Patent Publication WO 2006/059105,each of which is incorporated by reference in its entirety. In yet otheraspects of this embodiment, the retargeted endopeptidase activity beingdetected is from a non-naturally occurring retargeted endopeptidasevariant having, e.g., 1 or more, 2 or more, 3 or more, 4 or more, 5 ormore, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 20 ormore, 30 or more, 40 or more, 50 or more, or 100 or more contiguousamino acid substitutions, deletions, or additions relative to aretargeted endopeptidase of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQID NO:4, SEQ ID NO:130, or SEQ ID NO:131.

In yet another embodiment, the retargeted endopeptidase activity beingdetected is from an opioid retargeted endopeptidase. Non-limitingexamples of opioid re-targeted endopeptidase, or opioid-TVEMPs, aredescribed in, e.g., Keith A. Foster et al., Clostridial ToxinDerivatives Able To Modify Peripheral Sensory Afferent Functions, U.S.Pat. No. 5,989,545; J. Oliver Dolly et al., Activatable RecombinantNeurotoxins, U.S. Pat. No. 7,132,259; Stephan Donovan, Clostridial ToxinDerivatives and Methods For Treating Pain, U.S. Pat. No. 7,244,437;Stephan Donovan, Clostridial Toxin Derivatives and Methods For TreatingPain, U.S. Pat. No. 7,413,742; Stephan Donovan, Clostridial ToxinDerivatives and Methods For Treating Pain, U.S. Pat. No. 7,415,338;Lance E. Steward et al., Multivalent Clostridial Toxin Derivatives andMethods of Their Use, U.S. Pat. No. 7,514,088; Keith A. Foster, FusionProteins, U.S. Patent Publication 2008/0064092; Keith A. Foster, FusionProteins, U.S. Patent Publication 2009/0035822; Lance E. Steward et al.,Multivalent Clostridial Toxin Derivatives and Methods of Their Use, U.S.Patent Publication 2009/0048431; Keith A. Foster, Non-Cytotoxic ProteinConjugates, U.S. Patent Publication 2009/0162341; Keith A. Foster etal., Re-targeted Toxin Conjugates, International Patent Publication WO2005/023309; and Lance E. Steward, Modified Clostridial Toxins withEnhanced Translocation Capabilities and Altered Targeting Capabilitiesfor Non-Clostridial Toxin Target Cells, International Patent ApplicationWO 2008/008805; each of which is hereby incorporated by reference in itsentirety.

In yet another embodiment, the retargeted endopeptidase activity beingdetected is from a galanin retargeted endopeptidase. Non-limitingexamples of galanin re-targeted endopeptidase, or galanin-TVEMPs, aredescribed in, e.g., Steward, L. E. et al., Modified Clostridial Toxinswith Enhanced Translocation Capability and Enhanced Targeting Activity,U.S. patent application Ser. No. 11/776,043 (Jul. 11, 2007); Steward, L.E. et al., Modified Clostridial Toxins with Enhanced TranslocationCapabilities and Altered Targeting Activity For Clostridial Toxin TargetCells, U.S. patent application Ser. No. 11/776,052 (Jul. 11, 2007); andSteward, L. E. et al., Modified Clostridial Toxins with EnhancedTranslocation Capabilities and Altered Targeting Activity ForNon-Clostridial Toxin Target Cells, U.S. patent application Ser. No.11/776,075 (Jul. 11, 2007), each of which is incorporated by referencein its entirety.

Aspects of the present disclosure comprise, in part, a SNAP-25. As usedherein, the term “SNAP-25” refers to a naturally-occurring SNAP-25 or anon-naturally occurring SNAP-25 which is preferentially cleaved by aretargeted endopeptidase. As used herein, the term “preferentiallycleaved” refers to that the cleavage rate of SNAP-25 by a retargetedendopeptidase is at least one order of magnitude higher than thecleavage rate of any other substrate by a retargeted endopeptidase. Inaspects of this embodiment, the cleavage rate of SNAP-25 by a retargetedendopeptidase is at least two orders of magnitude higher, at least threeorders of magnitude higher, at least four orders of magnitude higher, orat least five orders of magnitude higher then that the cleavage rate ofany other substrate by retargeted endopeptidase.

As used herein, the term “naturally occurring SNAP-25” refers to anySNAP-25 produced by a naturally-occurring process, including, withoutlimitation, SNAP-25 isoforms produced from a post-translationalmodification, an alternatively-spliced transcript, or a spontaneousmutation, and SNAP-25 subtypes. A naturally occurring SNAP-25 includes,without limitation, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8,SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQID NO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ IDNO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ IDNO:24, or one that substitutes, deletes or adds, e.g., 1 or more, 2 ormore, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more,9 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50 or more,or 100 or more amino acids from SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7,SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQID NO:13, SEQ ID NO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ IDNO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ IDNO:23, or SEQ ID NO:24.

As used herein, the term “non-naturally occurring SNAP-25” refers to anySNAP-25 whose structure was modified with the aid of human manipulation,including, without limitation, a SNAP-25 produced by genetic engineeringusing random mutagenesis or rational design and a SNAP-25 produced by invitro chemical synthesis. Non-limiting examples of non-naturallyoccurring SNAP-25s are described in, e.g., Steward, L. E. et al., FRETProtease Assays for Clostridial Toxins, U.S. Pat. No. 7,332,567;Fernandez-Salas et al., Lipohilic Dye-based FRET Assays for ClostridialToxin Activity, U.S. Patent Publication 2008/0160561, each of which ishereby incorporated by reference in its entirety. A non-naturallyoccurring SNAP-25 may substitute, delete or add, e.g., 1 or more, 2 ormore, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more,9 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50 or more,or 100 or more amino acids from SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7,SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQID NO:13, SEQ ID NO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ IDNO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ IDNO:23, or SEQ ID NO:24.

Thus in an embodiment, a SNAP-25 is a naturally occurring SNAP-25. Inaspects of this embodiment, the SNAP-25 is a SNAP-25 isoform or aSNAP-25 subtype. In aspects of this embodiment, the naturally occurringSNAP-25 is the naturally occurring SNAP-25 of SEQ ID NO:5, SEQ ID NO:6,SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQID NO:12, SEQ ID NO:13, SEQ ID NO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ IDNO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ IDNO:22, SEQ ID NO:23, or SEQ ID NO:24. In other aspects of thisembodiment, the SNAP-25 is a naturally occurring SNAP-25 having, e.g.,at least 70% amino acid identity, at least 75%, at least 80%, at least85%, at least 90%, or at least 95% amino acid identity with SEQ ID NO:5,SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ IDNO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:14, SEQ ID NO:15, SEQ IDNO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ IDNO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24.

In another embodiment, a SNAP-25 is a non-naturally occurring SNAP-25.In other aspects of this embodiment, the SNAP-25 is a non-naturallyoccurring SNAP-25 having, e.g., at least 70%, at least 75%, at least80%, at least 85%, at least 90%, or at least 95% amino acid identitywith SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, or SEQ ID NO:4. In otheraspects of this embodiment, the SNAP-25 is a non-naturally occurringSNAP-25 having, e.g., 1 or more, 2 or more, 3 or more, 4 or more, 5 ormore, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 20 ormore, 30 or more, 40 or more, 50 or more, or 100 or more non-contiguousamino acid substitutions, deletions, or additions relative to SEQ IDNO:5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10,SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:14, SEQ ID NO:15,SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20,SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24. In yet otheraspects of this embodiment, the SNAP-25 is a non-naturally occurringSNAP-25 having, e.g., 1 or more, 2 or more, 3 or more, 4 or more, 5 ormore, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 20 ormore, 30 or more, 40 or more, 50 or more, or 100 or more contiguousamino acid substitutions, deletions, or additions relative to SEQ IDNO:5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10,SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:14, SEQ ID NO:15,SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20,SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24.

A SNAP-25 can be an endogenous SNAP-25 or an exogenous SNAP-25. As usedherein, the term “endogenous SNAP-25” refers to a SNAP-25 naturallypresent in the cell because it is naturally encoded within the cell'sgenome, such that the cell inherently expresses the SNAP-25 without theneed an external source of SNAP-25 or an external source of geneticmaterial encoding a SNAP-25. The expression of an endogenous SNAP-25 maybe with or without environmental stimulation such as, e.g., celldifferentiation. By definition, an endogenous SNAP-25 can only be anaturally-occurring SNAP-25 or variants thereof. For example, thefollowing established cell lines express an endogenous SNAP-25:BE(2)-M17, Kelly, LA1-55n, N1E-115, N4TG3, N18, Neuro-2a, NG108-15,PC12, SH-SY5Y, SiMa, SK-N-DZ, and SK-N-BE(2)-C.

As used herein, the term “exogenous SNAP-25” refers to a SNAP-25expressed in a cell through the introduction of an external source ofSNAP-25 or an external source of genetic material encoding a SNAP-25 byhuman manipulation. The expression of an exogenous SNAP-25 may be withor without environmental stimulation such as, e.g., celldifferentiation. As a non-limiting example, cells from an establishedcell line can express an exogenous SNAP-25 by transient or stablytransfection of a SNAP-25. As another non-limiting example, cells froman established cell line can express an exogenous SNAP-25 by proteintransfection of a SNAP-25. An exogenous SNAP-25 can be anaturally-occurring SNAP-25 or variants thereof, or a non-naturallyoccurring SNAP-25 or variants thereof.

Thus in an embodiment, cells from an established cell line express anendogenous SNAP-25. In aspects of this embodiment, the endogenousSNAP-25 expressed by cells from an established cell line is anaturally-occurring SNAP-25. In other aspects of this embodiment, theendogenous SNAP-25 expressed by cells from an established cell line isSEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ IDNO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:14, SEQ IDNO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ IDNO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24. In yetaspects of this embodiment, the endogenous SNAP-25 expressed by cellsfrom an established cell line is a naturally occurring SNAP-25, such as,e.g., a SNAP-25 isoform or a SNAP-25 subtype. In other aspects of thisembodiment, the endogenous SNAP-25 expressed by cells from anestablished cell line is a naturally occurring SNAP-25 having, e.g., atleast 70% amino acid identity, at least 75%, at least 80%, at least 85%,at least 90%, or at least 95% amino acid identity with SEQ ID NO:5, SEQID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ IDNO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:14, SEQ ID NO:15, SEQ IDNO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ IDNO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24.

In another embodiment, cells from an established cell line aretransiently or stably engineered to express an exogenous SNAP-25. In anaspect of this embodiment, cells from an established cell line aretransiently or stably engineered to express a naturally-occurringSNAP-25. In other aspects of this embodiment, cells from an establishedcell line are transiently or stably engineered to express thenaturally-occurring SNAP-25 of SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7,SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQID NO:13, SEQ ID NO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ IDNO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ IDNO:23, or SEQ ID NO:24. In yet other aspects of this embodiment, cellsfrom an established cell line are transiently or stably engineered toexpress a naturally occurring SNAP-25, such as, e.g., a SNAP-25 isoformor a SNAP-25 subtype. In still other aspects of this embodiment, cellsfrom an established cell line are transiently or stably engineered toexpress a naturally occurring SNAP-25 having, e.g., at least 70% aminoacid identity, at least 75%, at least 80%, at least 85%, at least 90%,or at least 95% amino acid identity with SEQ ID NO:5, SEQ ID NO:6, SEQID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ IDNO:12, SEQ ID NO:13, SEQ ID NO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ IDNO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ IDNO:22, SEQ ID NO:23, or SEQ ID NO:24.

In another aspect of the embodiment, cells from an established cell lineare transiently or stably engineered to express a non-naturallyoccurring SNAP-25. In other aspects of this embodiment, cells from anestablished cell line are transiently or stably engineered to express anon-naturally occurring SNAP-25 having, e.g., at least 70%, at least75%, at least 80%, at least 85%, at least 90%, or at least 95% aminoacid identity with SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8,SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQID NO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ IDNO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ IDNO:24. In other aspects of this embodiment, cells from an establishedcell line are transiently or stably engineered to express anon-naturally occurring SNAP-25 having, e.g., 1 or more, 2 or more, 3 ormore, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more,10 or more, 20 or more, 30 or more, 40 or more, 50 or more, or 100 ormore non-contiguous amino acid substitutions, deletions, or additionsrelative to SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ IDNO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ IDNO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ IDNO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ IDNO:24. In yet other aspects of this embodiment, cells from anestablished cell line are transiently or stably engineered to express anon-naturally occurring SNAP-25 having, e.g., 1 or more, 2 or more, 3 ormore, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more,10 or more, 20 or more, 30 or more, 40 or more, 50 or more, or 100 ormore contiguous amino acid substitutions, deletions, or additionsrelative to SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ IDNO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ IDNO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ IDNO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ IDNO:24.

Assays that detect the cleavage of a SNAP-25 after exposure to aretargeted endopeptidase can be used to assess whether a cell isexpressing an endogenous or exogenous SNAP-25. In these assays,generation of a SNAP-25 cleavage-product would be detected in cellsexpressing a SNAP-25 after retargeted endopeptidase treatment.Non-limiting examples of specific Western blot analysis, as well aswell-characterized reagents, conditions and protocols are readilyavailable from commercial vendors that include, without limitation,Amersham Biosciences, Piscataway, N.J.; Bio-Rad Laboratories, Hercules,Calif.; Pierce Biotechnology, Inc., Rockford, Ill.; Promega Corporation,Madison, Wis., and Stratagene, Inc., La Jolla, Calif. It is understoodthat these and similar assays for SNAP-25 cleavage can be useful inidentifying cells expressing an endogenous or an exogenous SNAP-25.

As non-limiting examples, Western blot analysis using an antibody thatrecognize a SNAP-25 cleavage product or both the cleaved and uncleavedforms of SNAP-25 can be used to assay for uptake of retargetedendopeptidase. Examples of α-SNAP-25 antibodies useful for these assaysinclude, without limitation, α-SNAP-25 mouse monoclonal antibody SMI-81(Sternberger Monoclonals Inc., Lutherville, Md.), mouse α-SNAP-25monoclonal antibody CI 71.1 (Synaptic Systems, Goettingen, Germany),α-SNAP-25 mouse monoclonal antibody CI 71.2 (Synaptic Systems,Goettingen, Germany), α-SNAP-25 mouse monoclonal antibody SP12 (Abcam,Cambridge, Mass.), α-SNAP-25 rabbit polyclonal antiserum (SynapticSystems, Goettingen, Germany), α-SNAP-25 rabbit polyclonal antiserum(Abcam, Cambridge, Mass.), and α-SNAP-25 rabbit polyclonal antiserumS9684 (Sigma, St Louis, Mo.).

Aspects of the present disclosure comprise, in part, a retargetedendopeptidase receptor. As used herein, the term “retargetedendopeptidase receptor” refers to either a naturally-occurringretargeted endopeptidase receptor or a non-naturally occurringretargeted endopeptidase receptor which preferentially interacts with aretargeted endopeptidase in a manner that elicits a retargetedendopeptidase activity response. As used herein, the term“preferentially interacts” refers to that the equilibrium dissociationconstant (KD) of retargeted endopeptidase for a retargeted endopeptidasereceptor is at least one order of magnitude less than that of retargetedendopeptidase for any other receptor at the cell surface. Theequilibrium dissociation constant, a specific type of equilibriumconstant that measures the propensity of an retargetedendopeptidase-retargeted endopeptidase receptor complex to separate(dissociate) reversibly into its component molecules, namely theretargeted endopeptidase and the retargeted endopeptidase receptor, isdefined as KD=Ka/Kd at equilibrium. The association constant (Ka) isdefined as Ka=[C]/[L][R] and the disassociation constant (Kd) is definedas Kd=[L][R]/[C], where [L] equals the molar concentration of retargetedendopeptidase, [R] is the molar concentration of a retargetedendopeptidase receptor, and [C] is the molar concentration of theendopeptidase-receptor complex, and where all concentrations are of suchcomponents when the system is at equilibrium. The smaller thedissociation constant, the more tightly bound the retargetedendopeptidase is to its receptor, or the higher the binding affinitybetween retargeted endopeptidase and retargeted endopeptidase receptor.In aspects of this embodiment, the disassociation constant of retargetedendopeptidase for its receptor is at least two orders of magnitude less,at least three orders of magnitude less, at least four orders ofmagnitude less, or at least five orders of magnitude less than that ofretargeted endopeptidase for any other receptor. In other aspects ofthis embodiment, the binding affinity of a retargeted endopeptidase thatpreferentially interacts with its receptor can have an equilibriumdisassociation constant (KD) of, e.g., of 500 nM or less, 400 nM orless, 300 nM or less, 200 nM, or less 100 nM or less. In other aspectsof this embodiment, the binding affinity of a retargeted endopeptidasethat preferentially interacts with its receptor can have an equilibriumdisassociation constant (KD) of, e.g., of 90 nM or less, 80 nM or less,70 nM or less, 60 nM, 50 nM or less, 40 nM or less, 30 nM or less, 20nM, or less 10 nM or less. As used herein, the term “elicits aretargeted endopeptidase activity response” refers to the ability of aretargeted endopeptidase receptor to interact with a retargetedendopeptidase to form a endopeptidase/receptor complex and thesubsequent internalization of that complex into the cell cytoplasm.

As used herein, the term “naturally occurring retargeted endopeptidasereceptor” refers to any retargeted endopeptidase receptor produced by anaturally-occurring process, including, without limitation, retargetedendopeptidase receptor isoforms produced from a post-translationalmodification, an alternatively-spliced transcript, or a spontaneousmutation, and retargeted endopeptidase receptor subtypes. A naturallyoccurring retargeted endopeptidase receptor includes, withoutlimitation, naturally occurring opioid receptors like a opiate-likereceptor 1 (ORL1), a δ-opioid receptor (DOR), a κ-opioid receptor (KOR),and a μ-opioid receptor (MOR), such as those described in ChristopherEvans et al., Opioid Receptor Genes, U.S. Pat. No. 6,265,563;Christopher Evans et al., Methods of Screening Modulators of OpiodReceptor Activity, U.S. Pat. No. 6,432,652; Christopher Evans et al.,Opioid Receptors and Methods of Use, U.S. Pat. No. 7,282,563; andChristopher Evans et al., Delta Opioid Receptor Proteins, U.S. PatentPublication 2008/0219925, each of which is hereby incorporated byreference in its entirety. Other examples of a naturally occurringretargeted endopeptidase receptor includes, without limitation, thegalanin receptor 1, the galanin receptor 2, and the galanin receptor 3.Naturally occurring opioid receptors from other vertebrate species areknow in the art, such as, e.g., primate, cow, dog, mouse, rat, chicken,and fish, and can be used in aspects of the present specification.

A naturally occurring ORL1 includes, without limitation, SEQ ID NO:25and SEQ ID NO:26, or one that substitutes, deletes or adds, e.g., 1 ormore, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more,8 or more, 9 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50or more, or 100 or more amino acids from SEQ ID NO:25 or SEQ ID NO:26. Anaturally occurring DOR includes, without limitation, SEQ ID NO:27 andSEQ ID NO:28, or one that substitutes, deletes or adds, e.g., 1 or more,2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 ormore, 9 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50 ormore, or 100 or more amino acids from SEQ ID NO:27 or SEQ ID NO:28. Anaturally occurring KOR includes, without limitation, SEQ ID NO:29 andSEQ ID NO:30, or one that substitutes, deletes or adds, e.g., 1 or more,2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 ormore, 9 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50 ormore, or 100 or more amino acids from SEQ ID NO:29 or SEQ ID NO:30. Anaturally occurring MOR includes, without limitation, SEQ ID NO:31, orone that substitutes, deletes or adds, e.g., 1 or more, 2 or more, 3 ormore, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more,10 or more, 20 or more, 30 or more, 40 or more, 50 or more, or 100 ormore amino acids from SEQ ID NO:31.

A naturally occurring galanin receptor 1 includes, without limitation,SEQ ID NO:136, SEQ ID NO:137, and SEQ ID NO:138, or one thatsubstitutes, deletes or adds, e.g., 1 or more, 2 or more, 3 or more, 4or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 ormore, 20 or more, 30 or more, 40 or more, 50 or more, or 100 or moreamino acids from SEQ ID NO:136, SEQ ID NO:137, or SEQ ID NO:138. Anaturally occurring galanin receptor 2 includes, without limitation, SEQID NO:139, or one that substitutes, deletes or adds, e.g., 1 or more, 2or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 ormore, 9 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50 ormore, or 100 or more amino acids from SEQ ID NO:139. A naturallyoccurring galanin receptor 3 includes, without limitation, SEQ IDNO:140, or one that substitutes, deletes or adds, e.g., 1 or more, 2 ormore, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more,9 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50 or more,or 100 or more amino acids from SEQ ID NO:140.

As used herein, the term “non-naturally occurring retargetedendopeptidase receptor variant” refers to any retargeted endopeptidasereceptor produced with the aid of human manipulation or design,including, without limitation, a retargeted endopeptidase receptorproduced by genetic engineering using random mutagenesis or rationaldesign and a retargeted endopeptidase receptor produced by chemicalsynthesis. Non-limiting examples of non-naturally occurring retargetedendopeptidase receptor variants include, e.g., conservative retargetedendopeptidase receptor variants, non-conservative retargetedendopeptidase receptor variants, retargeted endopeptidase receptorchimeric variants and active retargeted endopeptidase receptorfragments.

As used herein, the term “non-naturally occurring retargetedendopeptidase receptor” refers to any retargeted endopeptidase receptorwhose structure was modified with the aid of human manipulation,including, without limitation, a retargeted endopeptidase receptorproduced by genetic engineering using random mutagenesis or rationaldesign and a retargeted endopeptidase receptor produced by in vitrochemical synthesis. A non-naturally occurring retargeted endopeptidasereceptor may substitute, delete or add, e.g., 1 or more, 2 or more, 3 ormore, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more,10 or more, 20 or more, 30 or more, 40 or more, 50 or more, or 100 ormore amino acids from SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ IDNO:28, SEQ ID NO:29, SEQ ID NO:30, SEQ ID NO:31, SEQ ID NO:136, SEQ IDNO:137, SEQ ID NO:138, SEQ ID NO:139, or SEQ ID NO:140.

Thus in an embodiment, a retargeted endopeptidase receptor is anaturally occurring retargeted endopeptidase receptor such as, e.g.,ORL1, DOR, KOR, or MOR. In aspects of this embodiment, the retargetedendopeptidase receptor is a retargeted endopeptidase receptor isoform ora retargeted endopeptidase receptor subtype. In aspects of thisembodiment, the naturally occurring retargeted endopeptidase receptor isthe naturally occurring retargeted endopeptidase receptor of SEQ IDNO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, SEQ IDNO:30, or SEQ ID NO:31. In other aspects of this embodiment, theretargeted endopeptidase receptor is a naturally occurring retargetedendopeptidase receptor having, e.g., at least 70% amino acid identity,at least 75%, at least 80%, at least 85%, at least 90%, or at least 95%amino acid identity with SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQID NO:28, SEQ ID NO:29, SEQ ID NO:30, or SEQ ID NO:31.

In another embodiment, a retargeted endopeptidase receptor is anon-naturally occurring retargeted endopeptidase receptor, such as,e.g., a genetically-engineered ORL1, a genetically-engineered DOR, agenetically-engineered KOR, or a genetically-engineered MOR. In otheraspects of this embodiment, the retargeted endopeptidase receptor is anon-naturally occurring retargeted endopeptidase receptor having, e.g.,at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, orat least 95% amino acid identity with SEQ ID NO:25, SEQ ID NO:26, SEQ IDNO:27, SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30, or SEQ ID NO:31. Inother aspects of this embodiment, the retargeted endopeptidase receptoris a non-naturally occurring retargeted endopeptidase receptor having,e.g., 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more,7 or more, 8 or more, 9 or more, 10 or more, 20 or more, 30 or more, 40or more, 50 or more, or 100 or more non-contiguous amino acidsubstitutions, deletions, or additions relative to SEQ ID NO:25, SEQ IDNO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30, or SEQ IDNO:31. In yet other aspects of this embodiment, the retargetedendopeptidase receptor is a non-naturally occurring retargetedendopeptidase receptor having, e.g., 1 or more, 2 or more, 3 or more, 4or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 ormore, 20 or more, 30 or more, 40 or more, 50 or more, or 100 or morecontiguous amino acid substitutions, deletions, or additions relative toSEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29,SEQ ID NO:30, or SEQ ID NO:31.

In another embodiment, a retargeted endopeptidase receptor is anaturally occurring retargeted endopeptidase receptor such as, e.g.,galanin receptor 1, galanin receptor 2, or galanin receptor 3. Inaspects of this embodiment, the retargeted endopeptidase receptor is aretargeted endopeptidase receptor isoform or a retargeted endopeptidasereceptor subtype. In aspects of this embodiment, the naturally occurringretargeted endopeptidase receptor is the naturally occurring retargetedendopeptidase receptor of SEQ ID NO:136, SEQ ID NO:137, SEQ ID NO:138,SEQ ID NO:139, or SEQ ID NO:140. In other aspects of this embodiment,the retargeted endopeptidase receptor is a naturally occurringretargeted endopeptidase receptor having, e.g., at least 70% amino acididentity, at least 75%, at least 80%, at least 85%, at least 90%, or atleast 95% amino acid identity with SEQ ID NO:136, SEQ ID NO:137, SEQ IDNO:138, SEQ ID NO:139, or SEQ ID NO:140.

In another embodiment, a retargeted endopeptidase receptor is anon-naturally occurring retargeted endopeptidase receptor, such as,e.g., a genetically-engineered galanin receptor 1, agenetically-engineered galanin receptor 2, or a genetically-engineeredgalanin receptor 3. In other aspects of this embodiment, the retargetedendopeptidase receptor is a non-naturally occurring retargetedendopeptidase receptor having, e.g., at least 70%, at least 75%, atleast 80%, at least 85%, at least 90%, or at least 95% amino acididentity with SEQ ID NO:136, SEQ ID NO:137, SEQ ID NO:138, SEQ IDNO:139, or SEQ ID NO:140. In other aspects of this embodiment, theretargeted endopeptidase receptor is a non-naturally occurringretargeted endopeptidase receptor having, e.g., 1 or more, 2 or more, 3or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 ormore, 10 or more, 20 or more, 30 or more, 40 or more, 50 or more, or 100or more non-contiguous amino acid substitutions, deletions, or additionsrelative to SEQ ID NO:136, SEQ ID NO:137, SEQ ID NO:138, SEQ ID NO:139,or SEQ ID NO:140. In yet other aspects of this embodiment, theretargeted endopeptidase receptor is a non-naturally occurringretargeted endopeptidase receptor having, e.g., 1 or more, 2 or more, 3or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 ormore, 10 or more, 20 or more, 30 or more, 40 or more, 50 or more, or 100or more contiguous amino acid substitutions, deletions, or additionsrelative to SEQ ID NO:136, SEQ ID NO:137, SEQ ID NO:138, SEQ ID NO:139,or SEQ ID NO:140.

A retargeted endopeptidase receptor can be an endogenous retargetedendopeptidase receptor or an exogenous retargeted endopeptidasereceptor. As used herein, the term “endogenous retargeted endopeptidasereceptor” refers to a retargeted endopeptidase receptor naturallypresent in the cell because it is naturally encoded within the cell'sgenome, such that the cell inherently expresses the retargetedendopeptidase receptor without the need an external source of retargetedendopeptidase receptor or an external source of genetic materialencoding a retargeted endopeptidase receptor. Expression of anendogenous retargeted endopeptidase receptor may be with or withoutenvironmental stimulation such as e.g., cell differentiation or promoteractivation. For example, the following established cell lines express atleast one endogenous retargeted endopeptidase receptor: AGN P33,Neuro-2a, SiMa, and SK-N-DZ. An endogenous retargeted endopeptidasereceptor can only be a naturally-occurring retargeted endopeptidasereceptor or naturally-occurring variants thereof.

As used herein, the term “exogenous retargeted endopeptidase receptor”refers to a retargeted endopeptidase receptor expressed in a cellthrough the introduction of an external source of retargetedendopeptidase receptor or an external source of genetic materialencoding a retargeted endopeptidase receptor by human manipulation. Theexpression of an exogenous retargeted endopeptidase receptor may be withor without environmental stimulation such as, e.g., cell differentiationor promoter activation. As a non-limiting example, cells from anestablished cell line can express one or more exogenous retargetedendopeptidase receptors by transient or stably transfection of apolynucleotide molecule encoding a retargeted endopeptidase receptor,such as, e.g., an ORL1, a DOR, a KOR, a MOR, a galanin receptor 1, agalanin receptor 2, or a galanin receptor 3. As another non-limitingexample, cells from an established cell line can express one or moreexogenous retargeted endopeptidase receptors by protein transfection ofthe retargeted endopeptidase receptors, such as, e.g., an ORL1, a DOR, aKOR, a MOR, a galanin receptor 1, a galanin receptor 2, or a galaninreceptor 3. An exogenous retargeted endopeptidase receptor can be anaturally-occurring retargeted endopeptidase receptor or naturallyoccurring variants thereof, or non-naturally occurring retargetedendopeptidase receptor or non-naturally occurring variants thereof.

Thus in an embodiment, cells from an established cell line express anendogenous retargeted endopeptidase receptor. In aspects of thisembodiment, the endogenous retargeted endopeptidase receptor expressedby cells from an established cell line is a naturally-occurringretargeted endopeptidase receptor. In other aspects of this embodiment,the endogenous retargeted endopeptidase receptor expressed by cells froman established cell line is SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27,SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30, SEQ ID NO:31, SEQ ID NO:136,SEQ ID NO:137, SEQ ID NO:138, SEQ ID NO:139, or SEQ ID NO:140. In yetaspects of this embodiment, the endogenous retargeted endopeptidasereceptor expressed by cells from an established cell line is a naturallyoccurring retargeted endopeptidase receptor, such as, e.g., a retargetedendopeptidase receptor isoform or a retargeted endopeptidase receptorsubtype. In other aspects of this embodiment, the endogenous retargetedendopeptidase receptor expressed by cells from an established cell lineis a naturally occurring retargeted endopeptidase receptor having, e.g.,at least 70% amino acid identity, at least 75%, at least 80%, at least85%, at least 90%, or at least 95% amino acid identity with SEQ IDNO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, SEQ IDNO:30, SEQ ID NO:31, SEQ ID NO:136, SEQ ID NO:137, SEQ ID NO:138, SEQ IDNO:139, or SEQ ID NO:140.

In another embodiment, cells from an established cell line aretransiently or stably engineered to express an exogenous retargetedendopeptidase receptor. In an aspect of this embodiment, cells from anestablished cell line are transiently or stably engineered to express anaturally-occurring retargeted endopeptidase receptor. In other aspectsof this embodiment, cells from an established cell line are transientlyor stably engineered to express the naturally-occurring retargetedendopeptidase receptor of SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQID NO:28, SEQ ID NO:29, SEQ ID NO:30, SEQ ID NO:31, SEQ ID NO:136, SEQID NO:137, SEQ ID NO:138, SEQ ID NO:139, or SEQ ID NO:140. In yet otheraspects of this embodiment, cells from an established cell line aretransiently or stably engineered to express a naturally occurringretargeted endopeptidase receptor, such as, e.g., a retargetedendopeptidase receptor isoform or a retargeted endopeptidase receptorsubtype. In still other aspects of this embodiment, cells from anestablished cell line are transiently or stably engineered to express anaturally occurring retargeted endopeptidase receptor having, e.g., atleast 70% amino acid identity, at least 75%, at least 80%, at least 85%,at least 90%, or at least 95% amino acid identity with SEQ ID NO:25, SEQID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30, SEQ IDNO:31, SEQ ID NO:136, SEQ ID NO:137, SEQ ID NO:138, SEQ ID NO:139, orSEQ ID NO:140.

In another aspect of the embodiment, cells from an established cell lineare transiently or stably engineered to express a non-naturallyoccurring retargeted endopeptidase receptor. In other aspects of thisembodiment, cells from an established cell line are transiently orstably engineered to express a non-naturally occurring retargetedendopeptidase receptor having, e.g., at least 70%, at least 75%, atleast 80%, at least 85%, at least 90%, or at least 95% amino acididentity with SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28,SEQ ID NO:29, SEQ ID NO:30, SEQ ID NO:31, SEQ ID NO:136, SEQ ID NO:137,SEQ ID NO:138, SEQ ID NO:139, or SEQ ID NO:140. In other aspects of thisembodiment, cells from an established cell line are transiently orstably engineered to express a non-naturally occurring retargetedendopeptidase receptor having, e.g., 1 or more, 2 or more, 3 or more, 4or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 ormore, 20 or more, 30 or more, 40 or more, 50 or more, or 100 or morenon-contiguous amino acid substitutions, deletions, or additionsrelative to SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQID NO:29, SEQ ID NO:30, SEQ ID NO:31, SEQ ID NO:136, SEQ ID NO:137, SEQID NO:138, SEQ ID NO:139, or SEQ ID NO:140. In yet other aspects of thisembodiment, cells from an established cell line are transiently orstably engineered to express a non-naturally occurring retargetedendopeptidase receptor having, e.g., 1 or more, 2 or more, 3 or more, 4or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 ormore, 20 or more, 30 or more, 40 or more, 50 or more, or 100 or morecontiguous amino acid substitutions, deletions, or additions relative toSEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29,SEQ ID NO:30, SEQ ID NO:31, SEQ ID NO:136, SEQ ID NO:137, SEQ ID NO:138,SEQ ID NO:139, or SEQ ID NO:140.

In another embodiment, cells from an established cell line aretransiently or stably engineered to express an exogenous ORL1, anexogenous DOR, an exogenous KOR, an exogenous MOR, or any combinationthereof. In aspects of this embodiment, cells from an established cellline are transiently or stably engineered to express anaturally-occurring ORL1, a naturally-occurring DOR, anaturally-occurring KOR, a naturally-occurring MOR, or any combinationthereof. In yet other aspects of this embodiment, cells from anestablished cell line are transiently or stably engineered to express anon-naturally-occurring ORL1, a non-naturally-occurring DOR, anon-naturally-occurring KOR, a non-naturally-occurring MOR, or anycombination thereof. In still other aspects of this embodiment, cellsfrom an established cell line are transiently or stably engineered toexpress either a naturally-occurring ORL1 or a non-naturally-occurringORL1, a naturally-occurring DOR or a non-naturally-occurring DOR, anaturally-occurring KOR or a non-naturally-occurring KOR, anaturally-occurring MOR or a non-naturally-occurring MOR, or anycombination thereof.

In yet another embodiment, cells from an established cell line aretransiently or stably engineered to express an exogenous galaninreceptor 1, an exogenous galanin receptor 2, an exogenous galaninreceptor 3, or any combination thereof. In aspects of this embodiment,cells from an established cell line are transiently or stably engineeredto express a naturally-occurring galanin receptor 1, anaturally-occurring galanin receptor 2, a naturally-occurring galaninreceptor 3, or any combination thereof. In yet other aspects of thisembodiment, cells from an established cell line are transiently orstably engineered to express a non-naturally-occurring galanin receptor1, a non-naturally-occurring galanin receptor 2, anon-naturally-occurring galanin receptor 3, or any combination thereof.In still other aspects of this embodiment, cells from an establishedcell line are transiently or stably engineered to express either anaturally-occurring galanin receptor 1 or a non-naturally-occurringgalanin receptor 1, a naturally-occurring galanin receptor 2 or anon-naturally-occurring galanin receptor 2, a naturally-occurringgalanin receptor 3 or a non-naturally-occurring galanin receptor 3, orany combination thereof.

Cells that express one or more endogenous or exogenous re-targetedendopeptidase receptors can be identified by routine methods includingdirect and indirect assays for re-targeted endopeptidaseuptake. Assaysthat determine retargeted endopeptidase binding or uptake properties canbe used to assess whether a cell is expressing a retargetedendopeptidase receptor. Such assays include, without limitation,cross-linking assays using labeled retargeted endopeptidase, such as,e.g., [125I] retargeted endopeptidase, see, e.g., Noriko Yokosawa etal., Binding of Clostridium botulinum type C neurotoxin to differentneuroblastoma cell lines, 57 (1) Infect. Immun. 272-277 (1989); NorikoYokosawa et al., Binding of botulinum type CI, D and E neurotoxins toneuronal cell lines and synaptosomes, 29 (2) Toxicon 261-264 (1991); andTei-ichi Nishiki et al., Identification of protein receptor forClostridium botulinum type B neurotoxin in rat brain synaptosomes, 269(14) J. Biol. Chem. 10498-10503 (1994). Other non-limiting assaysinclude immunocytochemical assays that detect retargeted endopeptidasebinding using labeled or unlabeled antibodies, see, e.g., AtsushiNishikawa et al., The receptor and transporter for internalization ofClostridium botulinum type C progenitor toxin into HT-29 cells, 319 (2)Biochem. Biophys. Res. Commun. 327-333 (2004) and immunoprecipitationassays, see, e.g., Yukako Fujinaga et al., Molecular characterization ofbinding subcomponents of Clostridium botulinum type C progenitor toxinfor intestinal epithelial cells and erythrocytes, 150 (Pt 5)Microbiology 1529-1538 (2004), that detect bound re-targetedendopeptidase using labeled or unlabeled antibodies. Antibodies usefulfor these assays include, without limitation, antibodies selectedagainst retargeted endopeptidase and/or antibodies selected against aretargeted endopeptidase receptor, such as, e.g., ORL1, DOR, KOR, MOR,galanin receptor 1, galanin receptor 2, or galanin receptor 3. If theantibody is labeled, the binding of the molecule can be detected byvarious means, including Western blot analysis, direct microscopicobservation of the cellular location of the antibody, measurement ofcell or substrate-bound antibody following a wash step, flow cytometry,electrophoresis or capillary electrophoresis, employing techniqueswell-known to those of skill in the art. If the antibody is unlabeled,one may employ a labeled secondary antibody for indirect detection ofthe bound molecule, and detection can proceed as for a labeled antibody.It is understood that these and similar assays that determine retargetedendopeptidase uptake properties or characteristics can be useful inidentifying cells expressing endogenous or exogenous or retargetedendopeptidase receptors.

Assays that monitor the release of a molecule after exposure to aretargeted endopeptidase can also be used to assess whether a cell isexpressing one or more endogenous or exogenous retargeted endopeptidasereceptors. In these assays, inhibition of the molecule's release wouldoccur in cells expressing a retargeted endopeptidase receptor afterretargeted endopeptidase treatment. Well known assays include methodsthat measure inhibition of radio-labeled catecholamine release fromneurons, such as, e.g., [3H] noradrenaline or [3H] dopamine release, seee.g., A Fassio et al., Evidence for calcium-dependent vesiculartransmitter release insensitive to tetanus toxin and botulinum toxintype F, 90 (3) Neuroscience 893-902 (1999); and Sara Stigliani et al.,The sensitivity of catecholamine release to botulinum toxin C1 and Esuggests selective targeting of vesicles set into the readily releasablepool, 85 (2) J. Neurochem. 409-421 (2003), or measures catecholaminerelease using a fluorometric procedure, see, e.g., Anton de Paiva etal., A role for the interchain disulfide or its participating thiols inthe internalization of botulinum neurotoxin A revealed by a toxinderivative that binds to ecto-acceptors and inhibits transmitter releaseintracellularly, 268 (28) J. Biol. Chem. 20838-20844 (1993); Gary W.Lawrence et al., Distinct exocytotic responses of intact andpermeabilised chromaffin cells after cleavage of the 25-kDasynaptosomal-associated protein (SNAP-25) or synaptobrevin by botulinumtoxin A or B, 236 (3) Eur. J. Biochem. 877-886 (1996); and Patrick Foranet al., Botulinum neurotoxin C1 cleaves both syntaxin and SNAP-25 inintact and permeabilized chromaffin cells: correlation with its blockadeof catecholamine release, 35 (8) Biochemistry 2630-2636 (1996). Othernon-limiting examples include assays that measure inhibition of hormonerelease from endocrine cells, such as, e.g., anterior pituitary cells orovarian cells. It is understood that these and similar assays formolecule release can be useful in identifying cells expressingendogenous or exogenous or retargeted endopeptidase receptors.

Assays that detect the cleavage of a SNAP-25 substrate after exposure toa retargeted endopeptidase can also be used to assess whether a cell isexpressing one or more endogenous or exogenous retargeted endopeptidasereceptors. In these assays, generation of a SNAP-25 cleavage-product, ordisappearance of the intact SNAP-25, would be detected in cellsexpressing a retargeted endopeptidase receptor after a retargetedendopeptidase treatment. Non-limiting examples of specific Western blotanalysis, as well as well-characterized reagents, conditions andprotocols are readily available from commercial vendors that include,without limitation, Amersham Biosciences, Piscataway, N.J.; Bio-RadLaboratories, Hercules, Calif.; Pierce Biotechnology, Inc., Rockford,Ill.; Promega Corporation, Madison, Wis., and Stratagene, Inc., LaJolla, Calif. It is understood that these and similar assays for SNAP-25cleavage can be useful in identifying cells expressing endogenous orexogenous retargeted endopeptidase receptors.

As non-limiting examples, Western blot analysis using an antibody thatrecognizes SNAP-25-cleaved product or both the cleaved and uncleavedforms of SNAP-25 can be used to assay for uptake of a retargetedendopeptidase. Examples of α-SNAP-25 antibodies useful for these assaysinclude, without limitation, SMI-81 α-SNAP-25 mouse monoclonal antibody(Sternberger Monoclonals Inc., Lutherville, Md.), CI 71.1 mouseα-SNAP-25 monoclonal antibody (Synaptic Systems, Goettingen, Germany),CI 71.2 α-SNAP-25 mouse monoclonal antibody (Synaptic Systems,Goettingen, Germany), SP12 α-SNAP-25 mouse monoclonal antibody (Abcam,Cambridge, Mass.), α-SNAP-25 rabbit polyclonal antiserum (SynapticSystems, Goettingen, Germany), α-SNAP-25 rabbit polyclonal antiserumS9684 (Sigma, St. Louis, Mo.), and α-SNAP-25 rabbit polyclonal antiserum(Abcam, Cambridge, Mass.).

Aspects of the present disclosure provide cells that through geneticmanipulation or recombinant engineering are made to expresses anexogenous SNAP-25 and/or one or more exogenous retargeted endopeptidasereceptors. Cells useful to express an exogenous SNAP-25 and/or one ormore exogenous retargeted endopeptidase receptors through geneticmanipulation or recombinant engineering include neuronal cells andnon-neuronal cells that may or may not express an endogenous SNAP-25and/or one or more endogenous retargeted endopeptidase receptors. It isfurther understood that such genetically manipulated or recombinantlyengineered cells may express an exogenous SNAP-25 and one or moreexogenous retargeted endopeptidase receptors under control of aconstitutive, tissue-specific, cell-specific or inducible promoterelement, enhancer element or both. It is understood that any cell isuseful as long as the cell can be genetically manipulated orrecombinantly engineered to expresses an exogenous SNAP-25 and/or one ormore exogenous retargeted endopeptidase receptors and is capable ofundergoing retargeted endopeptidase activity.

Methods useful for introducing into a cell an exogenous polynucleotidemolecule encoding a component necessary for the cells to undergo theoverall cellular mechanism whereby a retargeted endopeptidaseproteolytically cleaves a SNAP-25 substrate, such as, e.g., a SNAP-25,an ORL1, a DOR, a KOR, or a MOR, include, without limitation,chemical-mediated delivery methods, such as, e.g., calciumphosphate-mediated, diethyl-aminoethyl (DEAE) dextran-mediated,lipid-mediated, polyethyleneimine (PEI)-mediated, polylysine-mediatedand polybrene-mediated; physical-mediated delivery methods, such as,e.g., biolistic particle delivery, microinjection, protoplast fusion andelectroporation; and viral-mediated delivery methods, such as, e.g.,retroviral-mediated transfection, see e.g., Introducing Cloned Genesinto Cultured Mammalian Cells, pp. 16.1-16.62 (Sambrook & Russell, eds.,Molecular Cloning A Laboratory Manual, Vol. 3, 3^(rd) ed. 2001); AlessiaColosimo et al., Transfer and Expression of Foreign Genes in MammalianCells, 29 (2) Biotechniques 314-318, 320-322, 324 (2000); PhilipWashbourne & A. Kimberley McAllister, Techniques for Gene Transfer intoNeurons, 12 (5) Curr. Opin. Neurobiol. 566-573 (2002); and CurrentProtocols in Molecular Biology, John Wiley and Sons, pp 9.16.4-9.16.11(2000), each of which is incorporated by reference in its entirety. Oneskilled in the art understands that selection of a specific method tointroduce a polynucleotide molecule into a cell will depend, in part, onwhether the cell will transiently or stably contain a componentnecessary for the cells to undergo the overall cellular mechanismwhereby a retargeted endopeptidase proteolytically cleaves a SNAP-25substrate. Non-limiting examples of polynucleotide molecule encoding acomponent necessary for the cells to undergo the overall cellularmechanism whereby a retargeted endopeptidase proteolytically cleaves aSNAP-25 substrate as follows: ORL1 polynucleotide molecule of SEQ IDNO:61 or SEQ ID NO:62; DOR polynucleotide molecule of SEQ ID NO:63 orSEQ ID NO:64; KOR polynucleotide molecule of SEQ ID NO:65 or SEQ IDNO:66; MOR polynucleotide molecule of SEQ ID NO:67; galanin receptor 1polynucleotide molecule of SEQ ID NO:141, SEQ ID NO:142, or SEQ IDNO:143, galanin receptor 2 polynucleotide molecule of SEQ ID NO:144, orgalanin receptor 3 polynucleotide molecule of SEQ ID NO:145, and SNAP-25polynucleotide molecule of SEQ ID NO:68, or SEQ ID NO:69.

Chemical-mediated delivery methods are well-known to a person ofordinary skill in the art and are described in, e.g., Martin Jordan &Florian Worm, Transfection of Adherent and Suspended Cells by CalciumPhosphate, 33 (2) Methods 136-143 (2004); Chun Zhang et al.,Polyethylenimine Strategies for Plasmid Delivery to Brain-Derived Cells,33 (2) Methods 144-150 (2004), each of which is hereby incorporated byreference in its entirety. Such chemical-mediated delivery methods canbe prepared by standard procedures and are commercially available, see,e.g., CellPhect Transfection Kit (Amersham Biosciences, Piscataway,N.J.); Mammalian Transfection Kit, Calcium phosphate and DEAE Dextran,(Stratagene, Inc., La Jolla, Calif.); Lipofectamine™ TransfectionReagent (Invitrogen, Inc., Carlsbad, Calif.); ExGen 500 Transfection kit(Fermentas, Inc., Hanover, Md.), and SuperFect and EffecteneTransfection Kits (Qiagen, Inc., Valencia, Calif.).

Physical-mediated delivery methods are well-known to a person ofordinary skill in the art and are described in, e.g., Jeike E. Biewengaet al., Plasmid-Mediated Gene Transfer in Neurons using the BiolisticsTechnique, 71 (1) J. Neurosci. Methods. 67-75 (1997); John O'Brien &Sarah C. R. Lummis, Biolistic and Diolistic Transfection: Using the GeneGun to Deliver DNA and Lipophilic Dyes into Mammalian Cells, 33 (2)Methods 121-125 (2004); M. Golzio et al., In Vitro and In Vivo ElectricField-Mediated Permeabilization, Gene Transfer, and Expression, 33 (2)Methods 126-135 (2004); and Oliver Gresch et al., New Non-Viral Methodfor Gene Transfer into Primary Cells, 33 (2) Methods 151-163 (2004),each of which is hereby incorporated by reference in its entirety.

Viral-mediated delivery methods are well-known to a person of ordinaryskill in the art and are described in, e.g., Chooi M. Lai et al.,Adenovirus and Adeno-Associated Virus Vectors, 21 (12) DNA Cell Biol.895-913 (2002); Ilya Frolov et al., Alphavirus-Based Expression Vectors:Strategies and Applications, 93 (21) Proc. Natl. Acad. Sci. U.S.A.11371-11377 (1996); Roland Wolkowicz et al., Lentiviral Vectors for theDelivery of DNA into Mammalian Cells, 246 Methods Mol. Biol. 391-411(2004); A. Huser & C. Hofmann, Baculovirus Vectors: Novel Mammalian CellGene-Delivery Vehicles and Their Applications, 3 (1) Am. J.Pharmacogenomics 53-63 (2003); Tiziana Tonini et al., TransientProduction of Retro viral- and Lentiviral-Based Vectors for theTransduction of Mammalian Cells, 285 Methods Mol. Biol. 141-148 (2004);Manfred Gossen & Hermann Bujard, Tight Control of Gene Expression inEukaryotic Cells by Tetracycline-Responsive Promoters, U.S. Pat. No.5,464,758; Hermann Bujard & Manfred Gossen, Methods for Regulating GeneExpression, U.S. Pat. No. 5,814,618; David S. Hogness, PolynucleotidesEncoding Insect Steroid Hormone Receptor Polypeptides and CellsTransformed With Same, U.S. Pat. No. 5,514,578; David S. Hogness,Polynucleotide Encoding Insect Ecdysone Receptor, U.S. Pat. No.6,245,531; Elisabetta Vegeto et al., Progesterone Receptor Having C.Terminal Hormone Binding Domain Truncations, U.S. Pat. No. 5,364,791;Elisabetta Vegeto et al., Mutated Steroid Hormone Receptors, Methods forTheir Use and Molecular Switch for Gene Therapy, U.S. Pat. No.5,874,534, each of which is hereby incorporated by reference in itsentirety. Such viral-mediated delivery methods can be prepared bystandard procedures and are commercially available, see, e.g.,ViraPower™ Adenoviral Expression System (Invitrogen, Inc., Carlsbad,Calif.) and ViraPower™ Adenoviral Expression System Instruction Manual25-0543 version A, Invitrogen, Inc., (Jul. 15, 2002); and AdEasy™Adenoviral Vector System (Stratagene, Inc., La Jolla, Calif.) andAdEasy™ Adenoviral Vector System Instruction Manual 064004f, Stratagene,Inc. Furthermore, such viral delivery systems can be prepared bystandard methods and are commercially available, see, e.g., BD™ Tet-Offand Tet-On Gene Expression Systems (BD Biosciences-Clonetech, Palo Alto,Calif.) and BD™ Tet-Off and Tet-On Gene Expression Systems User Manual,PT3001-1, BD Biosciences Clonetech, (Mar. 14, 2003), GeneSwitch™ System(Invitrogen, Inc., Carlsbad, Calif.) and GeneSwitch™ System AMifepristone-Regulated Expression System for Mammalian Cells version D,25-0313, Invitrogen, Inc., (Nov. 4, 2002); ViraPower™ LentiviralExpression System (Invitrogen, Inc., Carlsbad, Calif.) and ViraPower™Lentiviral Expression System Instruction Manual 25-0501 version E,Invitrogen, Inc., (Dec. 8, 2003); and Complete Control® RetroviralInducible Mammalian Expression System (Stratagene, La Jolla, Calif.) andComplete Control® Retroviral Inducible Mammalian Expression SystemInstruction Manual, 064005e.

Thus, in an embodiment, cells from an established cell line susceptibleto retargeted endopeptidase activity transiently contain apolynucleotide molecule encoding a component necessary for the cells toundergo the overall cellular mechanism whereby a retargetedendopeptidase proteolytically cleaves a SNAP-25 substrate. In anotherembodiment, cells from an established cell line susceptible toretargeted endopeptidase activity transiently contain a polynucleotidemolecule encoding a plurality of components necessary for the cells toundergo the overall cellular mechanism whereby a retargetedendopeptidase proteolytically cleaves a SNAP-25 substrate. In aspects ofthis embodiment, cells from an established cell line susceptible toretargeted endopeptidase activity transiently contain a polynucleotidemolecule encoding ORL1, DOR, KOR, MOR, or SNAP-25. In aspects of thisembodiment, cells from an established cell line susceptible toretargeted endopeptidase activity transiently contain the polynucleotidemolecule of SEQ ID NO:61, or SEQ ID NO:62 encoding ORL1. In otheraspects of this embodiment, cells from an established cell linesusceptible to retargeted endopeptidase activity transiently contain thepolynucleotide molecule of SEQ ID NO:63, or SEQ ID NO:64 encoding DOR.In yet other aspects of this embodiment, cells from an established cellline susceptible to retargeted endopeptidase activity transientlycontain the polynucleotide molecule of SEQ ID NO:65, or SEQ ID NO:66encoding KOR. In still other aspects of this embodiment, cells from anestablished cell line susceptible to retargeted endopeptidase activitytransiently contain the polynucleotide molecule of SEQ ID NO:67 encodingMOR.

In other aspects of this embodiment, cells from an established cell linesusceptible to retargeted endopeptidase activity transiently contain thepolynucleotide molecule of SEQ ID NO:141, SEQ ID NO:142, or SEQ IDNO:143 encoding Galanin receptor 1. In yet other aspects of thisembodiment, cells from an established cell line susceptible toretargeted endopeptidase activity transiently contain the polynucleotidemolecule of SEQ ID NO:144 encoding Galanin receptor 2. In still otheraspects of this embodiment, cells from an established cell linesusceptible to retargeted endopeptidase activity transiently contain thepolynucleotide molecule of SEQ ID NO:145 encoding Galanin receptor 3. Infurther aspects of this embodiment, cells from an established cell linesusceptible to retargeted endopeptidase activity transiently contain thepolynucleotide molecule of SEQ ID NO:68 or SEQ ID NO:69 encodingSNAP-25.

In another embodiment, cells from an established cell line susceptibleto retargeted endopeptidase activity stably contain a polynucleotidemolecule encoding a component necessary for the cells to undergo theoverall cellular mechanism whereby a retargeted endopeptidaseproteolytically cleaves a SNAP-25 substrate. In another embodiment,cells from an established cell line susceptible to retargetedendopeptidase activity stably contain a polynucleotide molecule encodinga plurality of components necessary for the cells to undergo the overallcellular mechanism whereby a retargeted endopeptidase proteolyticallycleaves a SNAP-25 substrate. In aspects of this embodiment, cells froman established cell line susceptible to retargeted endopeptidaseactivity stably contain a polynucleotide molecule encoding ORL1, DOR,KOR, MOR, or SNAP-25. In aspects of this embodiment, cells from anestablished cell line susceptible to retargeted endopeptidase activitystably contain the polynucleotide molecule of SEQ ID NO:61, or SEQ IDNO:62 encoding ORL1. In other aspects of this embodiment, cells from anestablished cell line susceptible to retargeted endopeptidase activitystably contain the polynucleotide molecule of SEQ ID NO:63, or SEQ IDNO:64 encoding DOR. In yet other aspects of this embodiment, cells froman established cell line susceptible to retargeted endopeptidaseactivity stably contain the polynucleotide molecule of SEQ ID NO:65, orSEQ ID NO:66 encoding KOR. In still other aspects of this embodiment,cells from an established cell line susceptible to retargetedendopeptidase activity stably contain the polynucleotide molecule of SEQID NO:67 encoding MOR.

In other aspects of this embodiment, cells from an established cell linesusceptible to retargeted endopeptidase activity stably contain thepolynucleotide molecule of SEQ ID NO:141, SEQ ID NO:142, or SEQ IDNO:143 encoding Galanin receptor 1. In yet other aspects of thisembodiment, cells from an established cell line susceptible toretargeted endopeptidase activity stably contain the polynucleotidemolecule of SEQ ID NO:144 encoding Galanin receptor 2. In yet otheraspects of this embodiment, cells from an established cell linesusceptible to retargeted endopeptidase activity stably contain thepolynucleotide molecule of SEQ ID NO:145 encoding Galanin receptor 3. Infurther aspects of this embodiment, cells from an established cell linesusceptible to retargeted endopeptidase activity stably contain thepolynucleotide molecule of SEQ ID NO:68 or SEQ ID NO:69 encodingSNAP-25.

As mentioned above, an exogenous component necessary for the cells toundergo the overall cellular mechanism whereby a retargetedendopeptidase proteolytically cleaves a SNAP-25 substrate, such as,e.g., a SNAP-25, an ORL1, a DOR, a KOR, a MOR, a Galanin receptor 1, aGalanin receptor 2, or a Galanin receptor 3, disclosed in the presentspecification can be introduced into a cell. Any and all methods usefulfor introducing such an exogenous component with a delivery agent into acell population can be useful with the proviso that this methodtransiently introduces the exogenous component disclosed in the presentspecification in at least 50% of the cells within a given cellpopulation. Thus, aspects of this embodiment can include a cellpopulation in which, e.g., at least 50%, at least 60%, at least 70%, atleast 80%, or at least 90% of the given cell population transientlycontains an exogenous component necessary for the cells to undergo theoverall cellular mechanism whereby a retargeted endopeptidaseproteolytically cleaves a SNAP-25 substrate, such as, e.g., a SNAP-25,an ORL1, a DOR, a KOR, a MOR, a Galanin receptor 1, a Galanin receptor2, or a Galanin receptor 3, disclosed in the present specification. Asused herein, the term “delivery agent” refers to any molecule thatenables or enhances internalization of a covalently-linked,non-covalently-linked or in any other manner associated with apolypeptide into a cell. Thus, the term “delivery agent” encompasses,without limitation, proteins, peptides, peptidomimetics, smallmolecules, polynucleotide molecules, liposomes, lipids, viruses,retroviruses and cells that, without limitation, transport a covalentlyor non-covalently linked molecule to the cell membrane, cell cytoplasmor nucleus. It further is understood that the term “delivery agent”encompasses molecules that are internalized by any mechanism, includingdelivery agents which function via receptor mediated endocytosis andthose which are independent of receptor mediated endocytosis.

A delivery agent can also be an agent that enables or enhances cellularuptake of a covalently linked component, like SNAP-25, ORL1, DOR, KOR,MOR, Galanin receptor 1, Galanin receptor 2, or Galanin receptor 3, suchas, e.g., by chemical conjugation or by genetically produced fusionproteins. Methods that covalently link delivery agents and methods ofusing such agents are described in, e.g., Steven F. Dowdy, ProteinTransduction System and Methods of Use Thereof, InternationalPublication No WO 00/34308; Gerard Chassaing & Alain Prochiantz,Peptides which can be Used as Vectors for the Intracellular Addressingof Active Molecules, U.S. Pat. No. 6,080,724; Alan Frankel et al.,Fusion Protein Comprising TAT-derived Transport Moiert, U.S. Pat. No.5,674,980; Alan Frankel et al., TAT-derived Transport PolypeptideConjugates, U.S. Pat. No. 5,747,641; Alan Frankel et al., TAT-derivedTransport Polypeptides and Fusion Proteins, U.S. Pat. No. 5,804,604;Peter F. J. O'Hare et al., Use of Transport Proteins, U.S. Pat. No.6,734,167; Yao-Zhong Lin & Jack J. Hawiger, Method for ImportingBiologically Active Molecules into Cells, U.S. Pat. No. 5,807,746;Yao-Zhong Lin & Jack J. Hawiger, Method for Importing BiologicallyActive Molecules into Cells, U.S. Pat. No. 6,043,339; Yao-Zhong Lin etal., Sequence and Method for Genetic Engineering of Proteins with CellMembrane Translocating Activity, U.S. Pat. No. 6,248,558; Yao-Zhong Linet al., Sequence and Method for Genetic Engineering of Proteins withCell Membrane Translocating Activity, U.S. Pat. No. 6,432,680; Jack J.Hawiger et al., Method for Importing Biologically Active Molecules intoCells, U.S. Pat. No. 6,495,518; Yao-Zhong Lin et al., Sequence andMethod for Genetic Engineering of Proteins with Cell MembraneTranslocating Activity, U.S. Pat. No. 6,780,843; Jonathan B. Rothbard &Paul A Wender, Method and Composition for Enhancing Transport AcrossBiological Membranes, U.S. Pat. No. 6,306,993; Jonathan B. Rothbard &Paul A Wender, Method and Composition for Enhancing Transport AcrossBiological Membranes, U.S. Pat. No. 6,495,663; and Pamela B. Davis etal., Fusion Proteins for Protein Delivery, U.S. Pat. No. 6,287,817, eachof which is incorporated by reference in its entirety.

A delivery agent can also be an agent that enables or enhances cellularuptake of a non-covalently associated component, like SNAP-25, ORL1,DOR, KOR, MOR, Galanin receptor 1, Galanin receptor 2, or Galaninreceptor 3. Methods that function in the absence of covalent linkage andmethods of using such agents are described in, e.g., Gilles Divita etal, Peptide-Mediated Transfection Agents and Methods of Use, U.S. Pat.No. 6,841,535; Philip L Feigner and Olivier Zelphati, IntracellularProtein Delivery Compositions and Methods of Use, U.S. PatentPublication No. 2003/0008813; and Michael Karas, Intracellular Deliveryof Small Molecules, Proteins and Nucleic Acids, U.S. Patent Publication2004/0209797, each of which is incorporated by reference in itsentirety. Such peptide delivery agents can be prepared and used bystandard methods and are commercially available, see, e.g. the CHARIOT™Reagent (Active Motif, Carlsbad, Calif.); BIO-PORTER® Reagent (GeneTherapy Systems, Inc., San Diego, Calif.), BIO TREK™ Protein DeliveryReagent (Stratagene, La Jolla, Calif.), and PRO-JECT™ ProteinTransfection Reagent (Pierce Biotechnology Inc., Rockford, Ill.).

Aspects of the present disclosure comprise, in part, a sample comprisinga retargeted endopeptidase. As used herein, the term “sample comprisinga retargeted endopeptidase” refers to any biological matter thatcontains or potentially contains an active retargeted endopeptidase. Avariety of samples can be assayed according to a method disclosed in thepresent specification including, without limitation, purified, partiallypurified, or unpurified retargeted endopeptidase; recombinant singlechain or di-chain retargeted endopeptidase with a naturally ornon-naturally occurring sequence; recombinant retargeted endopeptidasewith a modified protease specificity; recombinant retargetedendopeptidase with an altered cell specificity; bulk retargetedendopeptidase; a formulated retargeted endopeptidase product; and cellsor crude, fractionated or partially purified cell lysates from, e.g.,bacteria, yeast, insect, or mammalian sources; blood, plasma or serum;raw, partially cooked, cooked, or processed foods; beverages; animalfeed; soil samples; water samples; pond sediments; lotions; cosmetics;and clinical formulations. It is understood that the term sampleencompasses tissue samples, including, without limitation, mammaliantissue samples, livestock tissue samples such as sheep, cow and pigtissue samples; primate tissue samples; and human tissue samples. Suchsamples encompass, without limitation, intestinal samples such as infantintestinal samples, and tissue samples obtained from a wound. Asnon-limiting examples, a method of detecting picomolar amounts ofretargeted endopeptidase activity can be useful for determining thepresence or activity of a retargeted endopeptidase in a food or beveragesample; to assay a sample from a human or animal, for example, exposedto a retargeted endopeptidase or having one or more symptoms ofbotulism; to follow activity during production and purification of bulkretargeted endopeptidase; to assay a formulated retargeted endopeptidaseproduct used in pharmaceutical or cosmetics applications; or to assay asubject's blood serum for the presence or absence of neutralizingα-retargeted endopeptidase antibodies.

Thus, in an embodiment, a sample comprising a retargeted endopeptidaseis a sample comprising any amount of a retargeted endopeptidase. Inaspects of this embodiment, a sample comprising a retargetedendopeptidase comprises about 100 ng or less, about 10 ng or less, about1 ng or less, about 100 pg or less, about 10 pg or less, or about 1 pgor less of a retargeted endopeptidase. In other aspects of thisembodiment, a sample comprising a retargeted endopeptidase comprisesabout 1 μM or less, about 100 nM or less, about 10 nM or less, about 1nM or less, about 100 nM or less, about 10 nM or less, about 1 nM orless of a retargeted endopeptidase.

Aspects of the present disclosure comprise, in part, isolating from thetreated cell a SNAP-25 component comprising a SNAP-25 having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond. As used herein, the term “SNAP-25 component comprising a SNAP-25having a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond” refers to a cellular component containing the SNAP-25cleavage product. It is envisioned that any method suitable forenriching or isolating a SNAP-25 component can be useful, including,without limitation, cell lysing protocols, spin-column purificationprotocols, immunoprecipitation, affinity purification, and proteinchromatography.

Aspects of the present disclosure comprise, in part, an α-SNAP-25antibody linked to a solid phase support. As used herein, the term“solid-phase support” is synonymous with “solid phase” and refers to anymatrix that can be used for immobilizing an α-SNAP-25 antibody disclosedin the present specification. Non-limiting examples of solid phasesupports include, e.g., a tube; a plate; a column; pins or “dipsticks”;a magnetic particle, a bead or other spherical or fibrouschromatographic media, such as, e.g., agarose, sepharose, silica andplastic; and sheets or membranes, such as, e.g., nitrocellulose andpolyvinylidene fluoride (PVDF). The solid phase support can beconstructed using a wide variety of materials such as, e.g., glass,carbon, polystyrene, polyvinylchloride, polypropylene, polyethylene,dextran, nylon, diazocellulose, or starch. The solid phase supportselected can have a physical property that renders it readily separablefrom soluble or unbound material and generally allows unbound materials,such as, e.g., excess reagents, reaction by-products, or solvents, to beseparated or otherwise removed (by, e.g., washing, filtration,centrifugation, etc.) from solid phase support-bound assay component.Non-limiting examples of how to make and use a solid phase supports aredescribed in, e.g., Molecular Cloning, A Laboratory Manual, supra,(2001); and Current Protocols in Molecular Biology, supra, (2004), eachof which is hereby incorporated by reference in its entirety.

Aspects of the present disclosure comprise, in part, detecting thepresence of an antibody-antigen complex comprising an α-SNAP-25 antibodythat selectively binds to a SNAP-25 epitope having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond and aSNAP-25 cleavage product having a carboxyl-terminus at the P₁ residue ofthe BoNT/A cleavage site scissile bond. It is envisioned that anydetection system can be used to practice aspects of this disclosedimmuno-based method, with the provision that the signal to noise ratiocan distinguish to a statistically significant degree the signal fromthe antibody-antigen complex from the background signal. Non-limitingexamples of immuno-based detection systems include immunoblot analysis,like Western blotting and dot-blotting, immunoprecipitation analysis,enzyme-linked immunosorbent analysis (ELISA), and sandwich ELISA. Thedetection of the signal can be achieved using autoradiography withimaging or phosphorimaging (AU), chemiluminescense (CL),electrochemiluminescence (ECL), bioluminescence (BL), fluorescence,resonance energy transfer, plane polarization, colormetric, or flowcytometry (FC). Descriptions of immuno-based detection systems aredisclosed in, e.g., Michael M. Rauhut, Chemiluminescence, In Kirk-OthmerConcise Encyclopedia of Chemical Technology (Ed. Grayson, 3rd ed, JohnWiley and Sons, 1985); A. W. Knight, A Review of Recent Trends inAnalytical Applications of Electrogenerated Chemiluminescence, TrendsAnal. Chem. 18(1): 47-62 (1999); K. A. Fahnrich, et al., RecentApplications of Electrogenerated Chemiluminescence in Chemical Analysis,Talanta 54(4): 531-559 (2001); Commonly Used Techniques in MolecularCloning, pp. A8.1-A8-55 (Sambrook & Russell, eds., Molecular Cloning ALaboratory Manual, Vol. 3, 3^(rd) ed. 2001); Detection Systems, pp.A9.1-A9-49 (Sambrook & Russell, eds., Molecular Cloning A LaboratoryManual, Vol. 3, 3^(rd) ed. 2001); Electrogenerated Chemiluminescence,(Ed. Allen J. Bard, Marcel Dekker, Inc., 2004), each of which is herebyincorporated by reference in its entirety.

A sandwich ELISA (or sandwich immunoassay) is a method based on twoantibodies, which bind to different epitopes on the antigen. A captureantibody having a high binding specificity for the antigen of interest,is bound to a solid surface. The antigen is then added followed byaddition of a second antibody referred to as the detection antibody. Thedetection antibody binds the antigen to a different epitope than thecapture antibody. The antigen is therefore ‘sandwiched’ between the twoantibodies. The antibody binding affinity for the antigen is usually themain determinant of immunoassay sensitivity. As the antigenconcentration increases the amount of detection antibody increasesleading to a higher measured response. To quantify the extent of bindingdifferent reporter systems can be used, such as, e.g., an enzymeattached to the secondary antibody and a reporter substrate where theenzymatic reaction forms a readout as the detection signal. The signalgenerated is proportional to the amount of target antigen present in thesample. The reporter substrate used to measure the binding eventdetermines the detection mode. A spectrophotometric plate reader is usedfor colorimetric detection. Chemiluminescent andelectrochemiluminescence substrates have been developed which furtheramplify the signal and can be read on a luminescent reader. The reportercan also be a fluorescent readout where the enzyme step of the assay isreplaced with a fluorophore and the readout is then measured using afluorescent reader. Reagents and protocols necessary to perform an ECLsandwich ELISA are commercially available, including, without exception,MSD sandwich ELISA-ECL detection platform (Meso Scale Discovery,Gaithersburg, Md.).

Thus, in an embodiment, detecting the presence of an antibody-antigencomplex comprising an α-SNAP-25 antibody that selectively binds to aSNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond and a SNAP-25 cleavage product havinga carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond can be performed using an immuno-blot analysis, animmunoprecipitation analysis, an ELISA, or a sandwich ELISA. In aspectsof this embodiment, the detection is performed using a AU, CL, ECL, orBL immuno-blot analysis, a AU, CL, ECL, BL, or FC immunoprecipitationanalysis, a AU, CL, ECL, BL, or FC ELISA, or a AU, CL, ECL, BL, or FCsandwich ELISA.

Aspects of the present disclosure can be practiced in a singleplex ormultiplex fashion. An immuno-based method of detecting retargetedendopeptidase activity practiced in a single-plex fashion is one thatonly detects the presence of an antibody-antigen complex comprising anα-SNAP-25 antibody and a SNAP-25 cleavage product having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond. An immuno-based method of detecting retargeted endopeptidaseactivity practiced in a multiplex fashion is one that concurrentlydetects the presence of two or more antibody-antigen complexes; one ofwhich is the antibody-antigen complex comprising an α-SNAP-25 antibodyand a SNAP-25 cleavage product having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond; and the other(s) ofwhich is antibody-antigen complex to a second, third, fourth, etc.different protein. A second protein can be used, e.g., as an internalcontrol to minimize sample to sample variability by normalizing theamount of α-SNAP-25/SNAP-25 antibody-antigen complex detected to theamount of antibody-antigen complex detected for the second protein. Assuch, the second protein is usually one that is consistently expressedby the cell, such as a house-keeping protein. Non-limiting examples of auseful second protein, include, e.g., a Glyceraldehyde-3-PhosphateDehydrogenase (GAPDH), Syntaxin, cytokines. Methods of performing animmuno-based assay in a multiplex fashion are described in, e.g., U. B.Nielsen and B. H. Geierstanger, Multiplexed Sandwich Assays inMicroarray Format, J. Immunol. Methods. 290 (1-2): 107-120 2004); R.Barry and M, Soloviev, Quantitative Protein Profiling using AntibodyArrays, Proteomics, 4(12): 3717-3726 (2004); M. M. Ling et al.,Multiplexing Molecular Diagnostics and Immunoassays using EmergingMicroarray Technologies, Expert Rev Mol Diagn. 7(1): 87-98 (2007); S. X.Leng et al., ELISA and Multiplex Technologies for Cytokine Measurementin Inflammation and Aging Research, J Gerontol A Biol Sci Med Sci.63(8): 879-884 (2008), each of which is hereby incorporated by referencein its entirety.

Thus, in one embodiment, an immuno-based method of detecting retargetedendopeptidase activity practiced in a single-plex fashion by onlydetecting the presence of an antibody-antigen complex comprising anα-SNAP-25 antibody and a SNAP-25 cleavage product having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond. In another embodiment, immuno-based method of detecting retargetedendopeptidase activity practiced in a multiplex fashion by concurrentlydetecting the presence of an antibody-antigen complex comprising anα-SNAP-25 antibody and a SNAP-25 cleavage product having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond and at least one other antibody-antigen complex to a protein otherthan SNAP-25, such as, e.g., GAPDH or Syntaxin.

Aspects of the present disclosure provide, in part, a method ofdetermining re-targeted endopeptidase immunoresistance. As used herein,the term “re-targeted endopeptidase immunoresistance” means a mammalthat does not fully respond to a re-targeted endopeptidase therapy, orshows a reduced beneficial effect of a re-targeted endopeptidase therapybecause the immune response of that mammal, either directly orindirectly, reduces the efficacy of the therapy. A non-limiting exampleof reduced efficacy would be the presence in a mammal of at least oneneutralizing α-re-targeted endopeptidase antibody that binds to are-targeted endopeptidase in a manner that reduces or prevents thespecificity or activity of the re-targeted endopeptidase. As usedherein, the term “re-targeted endopeptidase therapy” means a treatment,remedy, cure, healing, rehabilitation or any other means ofcounteracting something undesirable in a mammal requiringneuromodulation using a re-targeted endopeptidase or administering to amammal one or more controlled doses of a medication, preparation ormixture of a re-targeted endopeptidase that has medicinal, therapeutic,curative, cosmetic, remedial or any other beneficial effect. Re-targetedendopeptidase therapy encompasses, without limitation, the use of anynaturally occurring or modified fragment thereof, in any formulation,combined with any carrier or active ingredient and administered by anyroute of administration.

Aspects of the present disclosure provide, in part, a test sampleobtained from a mammal being tested for the presence or absence ofα-re-targeted endopeptidase neutralizing antibodies. As used herein, theterm “test sample” refers to any biological matter that contains orpotentially contains at least one α-re-targeted endopeptidase antibody.An α-re-targeted endopeptidase antibody can be a neutralizingα-re-targeted endopeptidase antibody or a non-neutralizing α-re-targetedendopeptidase antibody. As used herein, the term “neutralizingα-re-targeted endopeptidase antibodies” means any α-re-targetedendopeptidase antibody that will, under physiological conditions, bindto a region of a re-targeted endopeptidase in such a manner as to reduceor prevent the re-targeted endopeptidase from exerting its effect in are-targeted endopeptidase therapy. As used herein, the term“non-neutralizing α-re-targeted endopeptidase antibodies” means anyα-re-targeted endopeptidase antibody that will, under physiologicalconditions, bind to a region of a re-targeted endopeptidase, but notprevent the re-targeted endopeptidase from exerting its effect in are-targeted endopeptidase therapy. It is envisioned that any and allsamples that can contain α-re-targeted endopeptidase antibodies can beused in this method, including, without limitation, blood, plasma, serumand lymph fluid. In addition, any and all organisms capable of raisingα-re-targeted endopeptidase antibodies against a re-targetedendopeptidase can serve as a source for a sample including, but notlimited to, birds and mammals, including mice, rats, goats, sheep,horses, donkeys, cows, primates and humans. Non-limiting examples ofspecific protocols for blood collection and serum preparation aredescribed in, e.g., Marjorie Schaub Di Lorenzo & Susan King Strasinger,BLOOD COLLECTION IN HEALTHCARE (F. A. Davis Company, 2001); and DianaGarza & Kathleen Becan-McBride, PHLEBOTOMY HANDBOOK: BLOOD COLLECTIONESSENTIALS (Prentice Hall, 6^(th) ed., 2002). These protocols areroutine procedures well within the scope of one skilled in the art andfrom the teaching herein. A test sample can be obtained from an organismprior to exposure to a re-targeted endopeptidase, after a singlere-targeted endopeptidase treatment, after multiple re-targetedendopeptidase treatments, before onset of resistance to a re-targetedendopeptidase therapy, or after onset of resistance to a re-targetedendopeptidase therapy.

Aspects of the present disclosure provide, in part, a control sample. Asused herein, the term “control sample” means any sample in which thepresence or absence of the test sample is known and includes bothnegative and positive control samples. With respect to neutralizingα-re-targeted endopeptidase antibodies, a negative control sample can beobtained from an individual who had never been exposed to re-targetedendopeptidase and may include, without limitation, a sample from thesame individual supplying the test sample, but taken before undergoing are-targeted endopeptidase therapy; a sample taken from a differentindividual never been exposed to re-targeted endopeptidase; a pooledsample taken from a plurality of different individuals never beenexposed to BoNT/A. With respect to neutralizing α-re-targetedendopeptidase antibodies, a positive control sample can be obtained froman individual manifesting re-targeted endopeptidase immunoresistance andincludes, without limitation, individual testing positive in apatient-based testing assays; individual testing positive in an in vivobioassay; and individual showing hyperimmunity, e.g., a re-targetedendopeptidase vaccinated individual.

It is further foreseen that α-re-targeted endopeptidase antibodies canbe purified from a sample. α-Re-targeted endopeptidase antibodies can bepurified from a sample, using a variety of procedures including, withoutlimitation, Protein A/G chromatography and affinity chromatography.Non-limiting examples of specific protocols for purifying antibodiesfrom a sample are described in, e.g., ANTIBODIES: A LABORATORY MANUAL(Edward Harlow & David Lane, eds., Cold Spring Harbor Laboratory Press,2^(nd) ed. 1998); USING ANTIBODIES: A LABORATORY MANUAL: PORTABLEPROTOCOL No. I (Edward Harlow & David Lane, Cold Spring HarborLaboratory Press, 1998); and MOLECULAR CLONING, A LABORATORY MANUAL,supra, (2001), which are hereby incorporated by reference. In addition,non-limiting examples of antibody purification methods as well aswell-characterized reagents, conditions and protocols are readilyavailable from commercial vendors that include, without limitation,Pierce Biotechnology, Inc., Rockford, Ill.; and Zymed Laboratories,Inc., South San Francisco, Calif. These protocols are routine procedureswell within the scope of one skilled in the art.

Thus, in an embodiment, a sample comprises blood. In aspect of thisembodiment, the sample comprises mouse blood, rat blood, goat blood,sheep blood, horse blood, donkey blood, cow blood, primate blood orhuman blood. In another embodiment, a sample comprises plasma. In anaspect of this embodiment, a test sample comprises mouse plasma, ratplasma, goat plasma, sheep plasma, horse plasma, donkey plasma, cowplasma, primate plasma or human plasma. In another embodiment, a samplecomprises serum. In an aspect of this embodiment, the sample comprisesmouse serum, rat serum, goat serum, sheep serum, horse serum, donkeyserum, cow serum, primate serum and human serum. In another embodiment,a sample comprises lymph fluid. In aspect of this embodiment, a samplecomprises mouse lymph fluid, rat lymph fluid, goat lymph fluid, sheeplymph fluid, horse lymph fluid, donkey lymph fluid, cow lymph fluid,primate lymph fluid or human lymph fluid. In yet another embodiment, asample is a test sample. In yet another embodiment, a sample is acontrol sample. In aspects of this embodiment, a control sample is anegative control sample or a positive control sample.

Aspects of the present disclosure provide, in part, comparing the amountof SNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond detected in step (d) to the amount ofSNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond detected in step (e). In an embodiment, theamount of SNAP-25 cleavage product in the test sample is higher ascompared to the amount of SNAP-25 cleavage product in the controlsample. In an aspect of this embodiment, a higher amount of SNAP-25cleavage product in the test sample as compared to a positive controlsample indicates a reduction in or lack of re-targeted endopeptidaseimmunoresistance in the mammal. In another aspect of this embodiment, anequivalent amount of SNAP-25 cleavage product in the test sample ascompared to a negative control sample indicates a reduction in or lackof re-targeted endopeptidase immunoresistance in the mammal. In anotherembodiment, the amount of SNAP-25 cleavage product in the test sample islower as compared to the amount of SNAP-25 cleavage product in thecontrol sample. In an aspect of this embodiment, a lower or equivalentamount of SNAP-25 cleavage product in the test sample as compared to apositive control sample indicates an increase in or presence ofre-targeted endopeptidase immunoresistance in the mammal. In anotheraspect of this embodiment, a lower amount of SNAP-25 cleavage product inthe test sample as compared to a negative control sample indicates anincrease in or presence of re-targeted endopeptidase immunoresistance inthe mammal.

It is envisioned that any and all assay conditions suitable fordetecting the present of a neutralizing α-re-targeted endopeptidaseantibody in a sample are useful in the methods disclosed in the presentspecification, such as, e.g., linear assay conditions and non-linearassay conditions. In an embodiment, the assay conditions are linear. Inan aspect of this embodiment, the assay amount of a re-targetedendopeptidase is in excess. In another aspect of this embodiment, theassay amount of a re-targeted endopeptidase is rate-limiting. In anotheraspect of this embodiment, the assay amount of a test sample israte-limiting.

Aspects of the present disclosure can also be described as follows:

-   1. A method of detecting retargeted endopeptidase activity, the    method comprising the steps of: a) treating a cell from an    established cell line with a sample comprising a retargeted    endopeptidase, wherein the cell from an established cell line is    susceptible to retargeted endopeptidase activity by a retargeted    endopeptidase; b) isolating from the treated cell a SNAP-25    component comprising a SNAP-25 cleavage product having a    carboxyl-terminus at the P₁ residue of the BoNT/A cleavage site    scissile bond; c) contacting the SNAP-25 component with an α-SNAP-25    antibody, wherein the α-SNAP-25 antibody binds an eptiope comprising    a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage site    scissile bond from a SNAP-25 cleavage product; and d) detecting the    presence of an antibody-antigen complex comprising the α-SNAP-25    antibody and the SNAP-25 cleavage product; wherein detection by the    antibody-antigen complex is indicative of retargeted endopeptidase    activity.-   2. A method of detecting retargeted endopeptidase activity, the    method comprising the steps of: a) treating a cell from an    established cell line with a sample comprising a retargeted    endopeptidase, wherein the cell from an established cell line is    susceptible to retargeted endopeptidaseactivity by a retargeted    endopeptidase; b) isolating from the treated cell a SNAP-25    component comprising a SNAP-25 cleavage product having a    carboxyl-terminus at the P₁ residue of the BoNT/A cleavage site    scissile bond; c) contacting the SNAP-25 component with an α-SNAP-25    antibody linked to a solid phase support, wherein the α-SNAP-25    antibody binds an eptiope comprising a carboxyl-terminus at the P₁    residue of the BoNT/A cleavage site scissile bond from a SNAP-25    cleavage product; and d) detecting the presence of an    antibody-antigen complex comprising the α-SNAP-25 antibody and the    SNAP-25 cleavage product; wherein detection by the antibody-antigen    complex is indicative of retargeted endopeptidase activity.-   3. A method of detecting retargeted endopeptidase activity, the    method comprising the steps of: a) treating a cell from an    established cell line with a sample comprising a retargeted    endopeptidase, wherein the cell from an established cell line is    susceptible to retargeted endopeptidase activity by a retargeted    endopeptidase; b) isolating from the treated cell a SNAP-25    component comprising a SNAP-25 cleavage product having a    carboxyl-terminus at the P₁ residue of the BoNT/A cleavage site    scissile bond; c) fixing the SNAP-25 component to a solid phase    support; d) contacting the SNAP-25 component with an α-SNAP-25    antibody, wherein the α-SNAP-25 antibody binds an eptiope comprising    a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage site    scissile bond from a SNAP-25 cleavage product; and e) detecting the    presence of an antibody-antigen complex comprising the α-SNAP-25    antibody and the SNAP-25 cleavage product; wherein detection by the    antibody-antigen complex is indicative of retargeted endopeptidase    activity.-   4. A method of detecting retargeted endopeptidase activity, the    method comprising the steps of: a) treating a cell from an    established cell line with a sample comprising a retargeted    endopeptidase, wherein the cell from an established cell line can    uptake retargeted endopeptidase; b) isolating from the treated cell    a SNAP-25 component comprising a SNAP-25 cleavage product having a    carboxyl-terminus at the P₁ residue of the BoNT/A cleavage site    scissile bond; c) contacting the SNAP-25 component with an α-SNAP-25    antibody, wherein the α-SNAP-25 antibody binds an eptiope comprising    a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage site    scissile bond from a SNAP-25 cleavage product; and d) detecting the    presence of an antibody-antigen complex comprising the α-SNAP-25    antibody and the SNAP-25 cleavage product; wherein detection by the    antibody-antigen complex is indicative of retargeted endopeptidase    activity.-   5. A method of detecting retargeted endopeptidase activity, the    method comprising the steps of: a) treating a cell from an    established cell line with a sample comprising a retargeted    endopeptidase, wherein the cell from an established cell line can    uptake retargeted endopeptidase; b) isolating from the treated cell    a SNAP-25 component comprising a SNAP-25 cleavage product having a    carboxyl-terminus at the P₁ residue of the BoNT/A cleavage site    scissile bond; c) contacting the SNAP-25 component with an α-SNAP-25    antibody linked to a solid phase support, wherein the α-SNAP-25    antibody binds an eptiope comprising a carboxyl-terminus at the P₁    residue of the BoNT/A cleavage site scissile bond from a SNAP-25    cleavage product; and d) detecting the presence of an    antibody-antigen complex comprising the α-SNAP-25 antibody and the    SNAP-25 cleavage product; wherein detection by the antibody-antigen    complex is indicative of retargeted endopeptidase activity.-   6. A method of detecting retargeted endopeptidase activity, the    method comprising the steps of: a) treating a cell from an    established cell line with a sample comprising a retargeted    endopeptidase, wherein the cell from an established cell line can    uptake retargeted endopeptidase; b) isolating from the treated cell    a SNAP-25 component comprising a SNAP-25 cleavage product having a    carboxyl-terminus at the P₁ residue of the BoNT/A cleavage site    scissile bond; c) fixing the SNAP-25 component to a solid phase    support; d) contacting the SNAP-25 component with an α-SNAP-25    antibody, wherein the α-SNAP-25 antibody binds an eptiope comprising    a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage site    scissile bond from a SNAP-25 cleavage product; and e) detecting the    presence of an antibody-antigen complex comprising the α-SNAP-25    antibody and the SNAP-25 cleavage product; wherein detection by the    antibody-antigen complex is indicative of retargeted endopeptidase    activity.-   7. A method of determining retargeted endopeptidase immunoresistance    in a mammal comprising the steps of: a) adding a retargeted    endopeptidase to a test sample obtained from a mammal being tested    for the presence or absence of α-retargeted endopeptidase    neutralizing antibodies; b) treating a cell from an established cell    line with the test sample, wherein the cell from an established cell    line is susceptible to retargeted endopeptidase activity; c)    isolating from the treated cells a SNAP-25 component comprising a    SNAP-25 cleavage product having a carboxyl-terminus at the P₁    residue of the BoNT/A cleavage site scissile bond; d) contacting the    SNAP-25 component with an α-SNAP-25 antibody, wherein the α-SNAP-25    antibody binds an eptiope comprising a carboxyl-terminus at the P₁    residue of the BoNT/A cleavage site scissile bond from a SNAP-25    cleavage product; e) detecting the presence of an antibody-antigen    complex comprising the α-SNAP-25 antibody and the SNAP-25 cleavage    product; f) repeating steps b-e with a negative control sample    instead of a test sample, the negative control sample comprising a    retargeted endopeptidase and a serum known not to contain    α-retargeted endopeptidase neutralizing antibodies; and g) comparing    the amount of antibody-antigen complex detected in step e to the    amount of antibody-antigen complex detected in step f, wherein    detection of a lower amount of antibody-antigen complex detected in    step e relative to the amount of antibody-antigen complex detected    in step f is indicative of the presence of α-retargeted    endopeptidase neutralizing antibodies.-   8. A method of determining retargeted endopeptidase immunoresistance    in a mammal comprising the steps of: a) adding a retargeted    endopeptidase to a test sample obtained from a mammal being tested    for the presence or absence of α-retargeted endopeptidase    neutralizing antibodies; b) treating a cell from an established cell    line with the test sample, wherein the cell from an established cell    line is susceptible to retargeted endopeptidase activity; c)    isolating from the treated cells a SNAP-25 component comprising a    SNAP-25 cleavage product having a carboxyl-terminus at the P₁    residue of the BoNT/A cleavage site scissile bond; d) contacting the    SNAP-25 component with an α-SNAP-25 antibody linked to a solid phase    support, wherein the α-SNAP-25 antibody binds an eptiope comprising    a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage site    scissile bond from a SNAP-25 cleavage product; e) detecting the    presence of an antibody-antigen complex comprising the α-retargeted    endopeptidase antibody and the SNAP-25 cleavage product; f)    repeating steps b-e with a negative control sample instead of a test    sample, the negative control sample comprising a re-targeted    endopeptidase and a serum known not to contain α-retargeted    endopeptidase neutralizing antibodies; and g) comparing the amount    of antibody-antigen complex detected in step e to the amount of    antibody-antigen complex detected in step f, wherein detection of a    lower amount of antibody-antigen complex detected in step e relative    to the amount of antibody-antigen complex detected in step f is    indicative of the presence of α-retargeted endopeptidase    neutralizing antibodies.-   9. A method of determining retargeted endopeptidase immunoresistance    in a mammal comprising the steps of: a) adding a retargeted    endopeptidase to a test sample obtained from a mammal being tested    for the presence or absence of α-retargeted endopeptidase    neutralizing antibodies; b) treating a cell from an established cell    line with the test sample, wherein the cell from an established cell    line is susceptible to retargeted endopeptidase activity; c)    isolating from the treated cells a SNAP-25 component comprising a    SNAP-25 cleavage product having a carboxyl-terminus at the P₁    residue of the BoNT/A cleavage site scissile bond; d) fixing the    SNAP-25 component to a solid phase support; e) contacting the    SNAP-25 component with an α-SNAP-25 antibody, wherein the α-SNAP-25    antibody binds an eptiope comprising a carboxyl-terminus at the P₁    residue of the BoNT/A cleavage site scissile bond from a SNAP-25    cleavage product; f) detecting the presence of an antibody-antigen    complex comprising the α-SNAP-25 antibody and the SNAP-25 cleavage    product; g) repeating steps b-f with a negative control sample    instead of a test sample, the negative control sample comprising a    re-targeted endopeptidase and a serum known not to contain    α-retargeted endopeptidase neutralizing antibodies; and h) comparing    the amount of antibody-antigen complex detected in step f to the    amount of antibody-antigen complex detected in step g, wherein    detection of a lower amount of antibody-antigen complex detected in    step f relative to the amount of antibody-antigen complex detected    in step g is indicative of the presence of α-retargeted    endopeptidase neutralizing antibodies.-   10. A method of determining retargeted endopeptidase    immunoresistance in a mammal comprising the steps of: a) adding a    retargeted endopeptidase to a test sample obtained from a mammal    being tested for the presence or absence of α-retargeted    endopeptidase neutralizing antibodies; b) treating a cell from an    established cell line with the test sample, wherein the cell from an    established cell line can uptake retargeted endopeptidase; c)    isolating from the treated cells a SNAP-25 component comprising a    SNAP-25 cleavage product having a carboxyl-terminus at the P₁    residue of the BoNT/A cleavage site scissile bond; d) contacting the    SNAP-25 component with an α-SNAP-25 antibody, wherein the α-SNAP-25    antibody binds an eptiope comprising a carboxyl-terminus at the P₁    residue of the BoNT/A cleavage site scissile bond from a SNAP-25    cleavage product; e) detecting the presence of an antibody-antigen    complex comprising the α-SNAP-25 antibody and the SNAP-25 cleavage    product; f) repeating steps b-e with a negative control sample    instead of a test sample, the negative control sample comprising a    retargeted endopeptidase and a serum known not to contain    α-re-targeted endopeptidase neutralizing antibodies; and g)    comparing the amount of antibody-antigen complex detected in step e    to the amount of antibody-antigen complex detected in step f,    wherein detection of a lower amount of antibody-antigen complex    detected in step e relative to the amount of antibody-antigen    complex detected in step f is indicative of the presence of    α-retargeted endopeptidase neutralizing antibodies.-   11. A method of determining retargeted endopeptidase    immunoresistance in a mammal comprising the steps of: a) adding a    re-targeted endopeptidase to a test sample obtained from a mammal    being tested for the presence or absence of α-re-targeted    endopeptidase neutralizing antibodies; b) treating a cell from an    established cell line with the test sample, wherein the cell from an    established cell line can uptake retargeted endopeptidase; c)    isolating from the treated cells a SNAP-25 component comprising a    SNAP-25 cleavage product having a carboxyl-terminus at the P₁    residue of the BoNT/A cleavage site scissile bond; d) contacting the    SNAP-25 component with an α-SNAP-25 antibody linked to a solid phase    support, wherein the α-SNAP-25 antibody binds an eptiope comprising    a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage site    scissile bond from a SNAP-25 cleavage product; e) detecting the    presence of an antibody-antigen complex comprising the α-SNAP-25    antibody and the SNAP-25 cleavage product; f) repeating steps b-e    with a negative control sample instead of a test sample, the    negative control sample comprising a retargeted endopeptidase and a    serum known not to contain α-re-targeted endopeptidase neutralizing    antibodies; and g) comparing the amount of antibody-antigen complex    detected in step e to the amount of antibody-antigen complex    detected in step f, wherein detection of a lower amount of    antibody-antigen complex detected in step e relative to the amount    of antibody-antigen complex detected in step f is indicative of the    presence of α-retargeted endopeptidase neutralizing antibodies.-   12. A method of determining retargeted endopeptidase    immunoresistance in a mammal comprising the steps of: a) adding a    retargeted endopeptidase to a test sample obtained from a mammal    being tested for the presence or absence of α-retargeted    endopeptidase neutralizing antibodies; b) treating a cell from an    established cell line with the test sample, wherein the cell from an    established cell line can uptake retargeted endopeptidase; c)    isolating from the treated cells a SNAP-25 component comprising a    SNAP-25 cleavage product having a carboxyl-terminus at the P₁    residue of the BoNT/A cleavage site scissile bond; d) fixing the    SNAP-25 component to a solid phase support; e) contacting the    SNAP-25 component with an α-SNAP-25 antibody, wherein the α-SNAP-25    antibody binds an eptiope comprising a carboxyl-terminus at the P₁    residue of the BoNT/A cleavage site scissile bond from a SNAP-25    cleavage product; f) detecting the presence of an antibody-antigen    complex comprising the α-SNAP-25 antibody and the SNAP-25 cleavage    product; g) repeating steps b-f with a negative control sample    instead of a test sample, the negative control sample comprising a    retargeted endopeptidase and a serum known not to contain    α-retargeted endopeptidase neutralizing antibodies; and h) comparing    the amount of antibody-antigen complex detected in step f to the    amount of antibody-antigen complex detected in step g, wherein    detection of a lower amount of antibody-antigen complex detected in    step f relative to the amount of antibody-antigen complex detected    in step g is indicative of the presence of α-retargeted    endopeptidase neutralizing antibodies.-   13. The method of 1-3 and 7-9, wherein the cell is susceptible to    retargeted endopeptidase activity by about 500 nM or less, by about    400 nM or less, by about 300 nM or less, by about 200 nM or less, by    about 100 nM or less of a retargeted endopeptidase.-   14. The method of 4-6 and 10-12, wherein the cell can uptake about    500 nM or less, by about 400 nM or less, by about 300 nM or less, by    about 200 nM or less, by about 100 nM or less of retargeted    endopeptidase.-   15. The method of 1-6, wherein the sample comprises about 100 ng or    less, about 10 ng or less, about 1 ng or less, 100 fg or less, 10 fg    or less, or 1 fg or less of a retargeted endopeptidase.-   16. The method of 1-6, wherein the sample comprises about 100 nM or    less, about 10 nM or less, about 1 nM or less, about 100 nM or less,    about 10 nM or less, about 1 nM or less, about 0.5 nM or less, or    about 0.1 nM or less, of a retargeted endopeptidase.-   17. The method of 1-12, wherein the presence of an antibody-antigen    complex is detected by an immuno-blot analysis, an    immunoprecipitation analysis, an ELISA, or a sandwich ELISA-   18. The method of 1-12, wherein the method has a signal-to-noise    ratio for the lower asymptote of at least 3:1, at least 5:1, at    least 10:1, at least 20:1, at least 50:1, or at least 100:1.-   19. The method of 1-12, wherein the method has a signal-to-noise    ratio for the higher asymptote of at least 10:1, at least 20:1, at    least 50:1, at least 100:1, at least 200:1, at least 300:1, at least    400:1, at least 500:1, or at least 600:1.-   20. The method of 1-12, wherein the method can detect the EC₅₀    activity of, e.g., at least 100 ng, at least 50 ng, at least 10 ng,    at least 5 ng, at least 100 pg, at least 50 pg, at least 10 pg, at    least 5 pg, at least 100 fg, at least 50 fg, at least 10 fg, or at    least 5 fg of a retargeted endopeptidase.-   21. The method of 1-12, wherein the method can detect the EC₅₀    activity of, e.g., at least 10 nM, at least 5 nM, at least 100 nM,    at least 50 nM, at least 10 nM, at least 5 nM, at least 1 nM, at    least 0.5 nM, or at least 0.1 nM of a retargeted endopeptidase.-   22. The method of 1-12, wherein the method has an LOD of, e.g., 10    pg or less, 9 pg or less, 8 pg or less, 7 pg or less, 6 pg or less,    5 pg or less, 4 pg or less, 3 pg or less, 2 pg or less, 1 pg or less    of a retargeted endopeptidase.-   23. The method of 1-12, wherein the method has an LOD of, e.g., 100    nM or less, 90 nM or less, 80 nM or less, 70 nM or less, 60 nM or    less, 50 nM or less, 40 nM or less, 30 nM or less, 20 nM or less, or    10 nM or less of a retargeted endopeptidase.-   24. The method of 1-12, wherein the method has an LOQ of, e.g., 10    pg or less, 9 pg or less, 8 pg or less, 7 pg or less, 6 pg or less,    5 pg or less, 4 pg or less, 3 pg or less, 2 pg or less, 1 pg or less    of a retargeted endopeptidase.-   25. The method of 1-12, wherein the method has an LOQ of, e.g., 100    nM or less, 90 nM or less, 80 nM or less, 70 nM or less, 60 nM or    less, 50 nM or less, 40 nM or less, 30 nM or less, 20 nM or less, or    10 nM or less of a retargeted endopeptidase.-   26. The method of 1-12, wherein the method can distinguish a    fully-active retargeted endopeptidase from a partially-active    retargeted endopeptidase having 70% or less, 60% or less, 50% or    less, 40% or less, 30% or less, 20% or less, or 10% or less the    activity of a fully-active retargeted endopeptidase A.-   27. The method of 1-12, wherein the α-SNAP-25 antibody binds an    eptiope comprising a carboxyl-terminus at the P₁ residue from the    BoNT/A cleavage site scissile bond from a SNAP-25 cleavage product.-   28. The method of 27, wherein the α-SNAP-25 antibody has an    association rate constant for an epitope not comprising a    carboxyl-terminus glutamine of the BoNT/A cleavage site scissile    bond from a SNAP-25 cleavage product of less than 1×10¹ M⁻¹ s⁻¹; and    wherein the α-SNAP-25 antibody has an equilibrium disassociation    constant for the epitope of less than 0.450 nM.-   29. The method of 27, wherein the isolated α-SNAP-25 antibody has a    heavy chain variable region comprising the amino acid sequence    selected from the group consisting of SEQ ID NO:72, SEQ ID NO:74,    SEQ ID NO:76, SEQ ID NO:80, and SEQ ID NO:82; and a light chain    variable region comprising the amino acid sequence selected from the    group consisting of SEQ ID NO:84, SEQ ID NO:86, SEQ ID NO:88, SEQ ID    NO:90, and SEQ ID NO:92.-   30. The method of 27, wherein the isolated α-SNAP-25 antibody    comprises at least the V_(H) CDR1 of SEQ ID NO:93, the V_(H) CDR1 of    SEQ ID NO:94, the V_(H) CDR1 of SEQ ID NO:95, the V_(H) CDR1 of SEQ    ID NO:118, the V_(H) CDR1 of SEQ ID NO:119, or the V_(H) CDR1 of SEQ    ID NO:120.-   32. The method of 27, wherein the isolated α-SNAP-25 antibody    comprises at least the V_(H) CDR2 of SEQ ID NO:96, the V_(H) CDR2 of    SEQ ID NO:97, the V_(H) CDR2 of SEQ ID NO:98, the V_(H) CDR2 of SEQ    ID NO:99, the V_(H) CDR2 of SEQ ID NO:121, the V_(H) CDR2 of SEQ ID    NO:122, or the V_(H) CDR2 of SEQ ID NO:123.-   33. The method of 27, wherein the isolated α-SNAP-25 antibody    comprises at least the V_(H) CDR3 of SEQ ID NO:100, the V_(H) CDR3    of SEQ ID NO:101, the V_(H) CDR3 of SEQ ID NO:102, or the V_(H) CDR3    of SEQ ID NO:124.-   34. The method of 27, wherein the isolated α-SNAP-25 antibody    comprises at least the V_(L) CDR1 of SEQ ID NO:103, the V_(L) CDR1    of SEQ ID NO:104, the V_(L) CDR1 of SEQ ID NO:105, the V_(L) CDR1 of    SEQ ID NO:106, the V_(L) CDR1 of SEQ ID NO:107, the V_(L) CDR1 of    SEQ ID NO:125, the V_(L) CDR1 of SEQ ID NO:126, the V_(L) CDR1 of    SEQ ID NO:127, the V_(L) CDR1 of SEQ ID NO:128, or the V_(L) CDR1 of    SEQ ID NO:129.-   35. The method of 27, wherein the isolated α-SNAP-25 antibody    comprises at least the V_(L) CDR2 of SEQ ID NO:108, the V_(L) CDR2    of SEQ ID NO:109, the V_(L) CDR2 of SEQ ID NO:110, the V_(L) CDR2 of    SEQ ID NO:111, or the V_(L) CDR2 of SEQ ID NO:112.-   36. The method of 27, wherein the isolated α-SNAP-25 antibody    comprises at least the V_(L) CDR3 of SEQ ID NO:113, the V_(L) CDR3    of SEQ ID NO:114, the V_(L) CDR3 of SEQ ID NO:115, the V_(L) CDR3 of    SEQ ID NO:116, or the V_(L) CDR3 of SEQ ID NO:117.-   37. The method of 27, wherein the isolated α-SNAP-25 antibody    comprises a heavy chain variable region comprising SEQ ID NO:93, SEQ    ID NO:121 and SEQ ID NO:100; and a light chain variable region    comprising SEQ ID NO:105, SEQ ID NO:110 and SEQ ID NO:115.-   38. The method of 27, wherein the isolated α-SNAP-25 antibody    selectively binds the SNAP-25 epitope of SEQ ID NO:32, SEQ ID NO:33,    SEQ ID NO:34, SEQ ID NO:35, SEQ ID NO:36, SEQ ID NO:37, SEQ ID    NO:147 or SEQ ID NO:148.-   39. The method of 27, wherein the isolated α-SNAP-25 antibody    selectively binds the SNAP-25 epitope of SEQ ID NO:39, SEQ ID NO:40,    SEQ ID NO:41, SEQ ID NO:42, SEQ ID NO:43, or SEQ ID NO:44.

EXAMPLES Example 1 Screening of Candidate Cell Lines for EndogenousRe-Targeted Endopeptidase Receptor Expression

The following example illustrates how to identify established cell linespossessing the re-targeted endopeptidase uptake capacity required todevelop a cell-based potency assay.

1. Growth of Stock Culture of Candidate Cell Lines.

To grow the cell lines, a suitable density of cells from the cell linebeing tested were plated in a 162 cm² tissue culture flask containing 30mL of a suitable growth medium (see Table 1), and grown in a 37° C.incubator under 5% or 10% carbon dioxide until cells reached the desireddensity.

TABLE 1 Media Used in Cell Line Screening. Cell Line Serum Growth MediaComposition SiMa and RPMI 1640, 10% fetal bovine serum, 1%Penicillin-Streptomycin, 2 mM L-Glutamine SiMa clones PC12 RPMI 1640, 5%heat-inactivated fetal bovine serum, 10% equine serum, 2 mM GlutaMAX ™,10 mM HEPES, 1 mM sodium pyruvate, 1% Penicillin-Streptomycin N18 90%DMEM, 10% heat-inactivated fetal bovine serum, 2 mM Glutamine, 2 mMglucose ND8/34 NG108-15 SK-N-DZ 90% DMEM, 10% heat-inactivated fetalbovine serum, 4 mM Glutamine, 4 mM glucose, SK-N-F1 0.1 mM non-essentialamino acids, 1.5 g/L NaHCO₃ SK-N-SH BE(2)-C EMEM(11090-081, Gibco),Ham's F12 (11765-054, Gibco), 10% heat-inactivated fetal SK-N-BE(2)bovine serum, 2 mM Glutamine, 0.1 mM non-essential amino acids, SH-SY5YND3, ND7, DMEM media with 2 mM Glutamine (Invitrogen, Cat #. 11885), 10%Fetal Bovine Serum ND15 (Invitrogen, Cat #. 16140), and 1xantibiotic/antimycotic Neuro-2a EMEM, 10% heat-inactivated fetal bovineserum, 2 mM Glutamine, 0.1 mM non-essential amino acids, 1.5 g/L NaHCO₃,1 mM Sodium pyruvate

2. Screening of Cells Expressing Target Receptor on Cell Surface.

The cell lines were screened for the presence of the desired targetreceptor using flow cytometry and/or ligand binding assays. Although theexamples below used reagents to identify opioid or opioid-like receptorin the plasma membrane, the approaches disclosed below can be used toidentify the cognate receptor for any of re-targeted endopeptidase.

a. Identification of Cell Lines Using Flow Cytometry.

To identify cells comprising established cell lines that express targetreceptors for a retargeted endopeptidase on the cell surface, flowcytometry analysis was conducted. Cells for each candidate cell linewere grown as described in Section 1, trypson-treated, washed instaining buffer comprising 1×PBS, 0.5% BSA, and centrifuged at 1200 rpmfor 3 minutes. Pelleted cells were resuspended in staining buffer andabout 2.0×10⁶ cells were transferred to new tubes, two for each receptortested. To screen for the presence of an opioid or opiod-like receptors,about 2.0-5.0 μL of α-ORL-1 RA14133 (Neuromics, Edina, Minn.), α-DORrabbit polyclonal antibody RA10101 (Neuromics, Edina, Minn.), α-KORrabbit polyclonal antibody RA10103 (Neuromics, Edina, Minn.), or α-MORrabbit polyclonal antibody RA10104 (Neuromics, Edina, Minn.), was addedto one tube and the mixture was incubated at 4° C. for 1 hour. Thesecond tube was incubated at 4° C. for 1 hour without any antibodies andserved as a negative control. After the antibody incubation, 1.0 mL ofstaining buffer was added to each tube and centrifuge at 1200 rpm for 3minutes. The cell pellet was washed once more with 1.0 mL of stainingbuffer. The cell pellet was resuspend in 200 μL of staining buffer, and2.0 μL of goat anti-rabbit IgG FITC antibody was added to each tube andincubated at 4° C. for 1 hour in the dark. After incubation with thesecondary antibody, 1.0 mL of staining buffer was added to each tube andcentrifuge at 1200 rpm for 3 minutes. The cell pellet was washed oncemore with 1.0 mL of staining buffer and the pellet resuspend in 500 μLof staining buffer. The sample was analyzed using a flow cytometer andthe data was displayed as an overlay the anti-receptor antibody stainingover the rabbit IgG FITC staining.

The results indicate that. Of the cell lines tested, ORL-1 was expressedon the cell surface of about 50% of the cells comprising SiMa, SiMaP>33, clone H10, ND7, and SK-N-DZ established cell lines; was expressedon the cell surface of between about 25% to about 50% of the cellscomprising SH-SY5Y and ND15 established cell lines; and was expressed onthe cell surface of less than about 25% of the cells comprising ND3,NDB, N18, and Neuro-2a established cell lines (Table 2). The resultsalso indicate that KOR was expressed on the cell surface of about 50% ofthe cells comprising SH-SY5Y and ND7 established cell lines; wasexpressed on the cell surface of between about 25% to about 50% of thecells comprising SiMa clone H10, SiMa P>33, ND15, and Neuro-2aestablished cell lines; and was expressed on the cell surface of lessthan about 25% of the cells comprising ND3, ND8, and N18 establishedcell lines (Table 2). The results also revealed that MOR was expressedon the cell surface of about 50% of the cells comprising ND7, ND15, andSiMa P>33 established cell lines; was expressed on the cell surface ofbetween about 25% to about 50% of the cells comprising SH-SY5Y, SiMaclone H10, ND8, and Neuro-2a established cell lines; and was expressedon the cell surface of less than about 25% of the cells comprising ND3and N18 established cell lines (Table 2). The α-DOR rabbit polyclonalantibody RA10101 failed to work properly and no useable data wasgenerated.

b. Identification of Cell Lines Using Ligand Binding.

To identify cells comprising established cell lines that express targetreceptors for a retargeted endopeptidase on the cell surface, ligandbinding analysis was conducted. Cells from the candidate cell lines tobe tested were seeded on a black-clear bottom 96-well plate for about 4hours to promote attachment. To screen for the presence of an opioid oropiod-like receptors, media was then aspirated from each well andreplaced with 50 μL of ligand solution containing either 0 (untreatedcontrol), 0.001 nM, 0.01 nM, 0.1 nM, or 1 nM of FAM-nociceptin (PhoenixPharmaceuticals, Inc, Burlingame, Calif.); or either 0 (untreatedcontrol), 0.001 nM, 0.01 nM, 0.1 nM, or 1 nM of FAM-dynorphin A (PhoenixPharmaceuticals, Inc, Burlingame, Calif.). Cells were incubated with theligand solution for 1 hour in the 37° C. incubator under 5% carbondioxide. The cells were washed to remove unbound ligand by washing thecells three times with 100 μL of 1×PBS. The plate was scanned on theTyphoon (Ex 488 and Em 520 nm), and then read on the M5 Plate Reader (Ex495 and Em 520 nm) for RFU signals. The results indicate that cellscomprising the SiMa clone H10, SH-SY5Y, and SK-N-DZ established celllines bound nociceptin, whereas cells comprising the SiMa clone H10 alsobound Dynorphin (Table 2).

TABLE 2 Cell lines Expressing Target Receptors on Cell Surface CellLines Identified Flow Cytometry Target More than 50% 25% to 50% Lessthan 50% Ligand Binding Receptor Expression Expression ExpressionNociceptin Dynorphin A ORL-1 AGN P33, SiMa, SH-SY5Y, ND15 ND3, ND8, N18,SiMa clone — SiMa clone H10, Neuro-2a H10, SH-SY5Y, ND7, SK-N-DZ SK-N-DZDOR ND ND ND ND ND KOR SH-SY5Y, ND7 SiMa clone H10, ND3, ND8, N18 — SiMaclone H10 AGN P33, ND15, Neuro-2a MOR ND7, ND15, AGN SH-SY5Y, SiMa ND3,N18 ND ND P33 clone H10, ND8, Neuro-2a

Using a similar approach, cell lines comprising cells having cognatereceptors for other re-targeted endopeptidases can be identified byFAM-labeling the targeting domain for these endopeptidases and screeningcell lines as described above.

3. Single Dose Screening of Candidate Cell Lines Using Re-TargetedEndopeptidase Molecule.

To determine whether a cell line was able to uptake the appropriatere-targeted endopeptidase molecule, a suitable density of cells from astock culture of the cell line being tested was plated into the wells of24-well tissue culture plates containing 1 mL of an appropriate serumgrowth medium (Table 1). The cells were grown in a 37° C. incubatorunder 5% carbon dioxide until cells reached the desired density(approximately 18 to 24 hours). To assess the uptake of an opioidre-targeted endopeptidase, the growth media was aspirated from each welland replaced with either 1) fresh growth media containing no opioidre-targeted endopeptidase (untreated cell line) or 2) fresh growth mediacontaining 30 nM for the nociceptin re-targeted endopeptidase (Noc/A) or100 nM for the dynorphin re-targeted endopeptidase (Dyn/A) (treated cellline). After an overnight incubation, the cells were washed byaspirating the growth media and rinsing each well with 200 μL of 1×PBS.To harvest the cells, the 1×PBS was aspirated, the cells were lysed byadding 50 μL of 2×SDS Loading Buffer, the lysate was transferred to aclean test tube and the sample was heated to 95° C. for 5 minutes.

To detect for the presence of both uncleaved SNAP-25 substrate andcleaved SNAP-25 products, an aliquot from each harvested sample wasanalyzed by Western blot. In this analysis, a 12 μL aliquot of theharvested sample was separated by MOPS polyacrylamide gelelectrophoresis using NuPAGE® Novex 12% Bis-Tris precast polyacrylamidegels (Invitrogen Inc., Carlsbad, Calif.) under denaturing, reducingconditions. Separated peptides were transferred from the gel ontopolyvinylidene fluoride (PVDF) membranes (Invitrogen Inc., Carlsbad,Calif.) by Western blotting using a TRANS-BLOT® SD semi-dryelectrophoretic transfer cell apparatus (Bio-Rad Laboratories, Hercules,Calif.). PVDF membranes were blocked by incubating at room temperaturefor 2 hours in a solution containing Tris-Buffered Saline (TBS) (25 mM2-amino-2-hydroxymethyl-1,3-propanediol hydrochloric acid (Tris-HCl)(pH7.4), 137 mM sodium chloride, 2.7 mM potassium chloride), 0.1% TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate), 2% Bovine Serum Albumin(BSA), 5% nonfat dry milk. Blocked membranes were incubated at 4° C. forovernight in TBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitanmonolaureate), 2% BSA, and 5% nonfat dry milk containing either 1) a1:5,000 dilution of an α-SNAP-25 mouse monoclonal antibody as theprimary antibody (SMI-81; Sternberger Monoclonals Inc., Lutherville,Md.); or 2) a 1:5,000 dilution of S9684 α-SNAP-25 rabbit polyclonalantiserum as the primary antibody (Sigma, St. Louis, Mo.). Bothα-SNAP-25 mouse monoclonal and rabbit polyclonal antibodies can detectboth the uncleaved SNAP-25 substrate and the SNAP-25 cleavage product,allowing for the assessment of overall SNAP-25 expression in each cellline and the percent of SNAP-25 cleaved after re-targeted endopeptidasetreatment as a parameter to assess the amount of re-targetedendopeptidase uptake. Primary antibody probed blots were washed threetimes for 15 minutes each time in TBS, TWEEN-20® (polyoxyethylene (20)sorbitan monolaureate). Washed membranes were incubated at roomtemperature for 2 hours in TBS, 0.1% TWEEN-20® (polyoxyethylene (20)sorbitan monolaureate), 2% BSA, and 5% nonfat dry milk containingeither 1) a 1:10,000 dilution of goat polyclonal anti-mouseimmunoglobulin G, heavy and light chains (IgG, H+L) antibody conjugatedto horseradish peroxidase (Zymed, South San Francisco, Calif.) as asecondary antibody; or 2) a 1:10,000 dilution of goat polyclonalanti-rabbit immunoglobulin G, heavy and light chains (IgG, H+L) antibodyconjugated to horseradish peroxidase (Zymed, South San Francisco,Calif.) as a secondary antibody. Secondary antibody-probed blots werewashed three times for 15 minutes each time in TBS, 0.1% TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate). Signal detection of thelabeled SNAP-25 products were visualized using the ECL Plus™ WesternBlot Detection System (GE Healthcare, Amersham Biosciences, Piscataway,N.J.) and the membrane was imaged and the percent of cleaved quantifiedwith a Typhoon 9410 Variable Mode Imager and Imager Analysis software(GE Healthcare, Amersham Biosciences, Piscataway, N.J.). The choice ofpixel size (100 to 200 pixels) and PMT voltage settings (350 to 600,normally 400) depended on the individual blot.

Based on the detection of SNAP-25 cleavage product, the following celllines exhibited uptake of 30 nM Noc/A: BE(2)-C, N18TG2, Neuro-2a, SiMa,SK-N-BE(2)-C, and SK-N-DZ (Table 3); whereas the following cell linesexhibited uptake of 100 nM Dyn/A: N18TG2, Neuro-2a, PC12, and SiMa. Someof these sensitive cell lines were tested with lower doses of compoundsand/or with full dose responses.

TABLE 3 Single-Dose Screening of Candidate Cell Lines Using RetargetedNoc/A and Dyn/A 30 nM 100 nM Noc/A Dyn/A Cell Line Description SourceUptake Uptake BE(2)-C Human neuroblastoma ATCC CRL-2268 Yes NT N18TG2Mouse neuroblastoma DSMZ ACC 103 Yes Yes ND3 Mouse neuroblastoma/primaryneonatal rat ECACC 92090901 NDA NDA DRG hybrid ND7/23 Mouseneuroblastoma/primary rat DRG ECACC 92090903 No No hybrid ND8 Mouseneuroblastoma/primary neonatal rat ECACC 92090904 NDA NDA DRG hybridND15 Mouse neuroblastoma/primary neonatal rat ECACC 92090907 No No DRGhybrid Neuro-2a Mouse neuroblastoma ATCC CCL-131 Yes Yes NG108-15 Mouseneuroblastoma/rat glioma hybrid ECACC 88112302 No NT PC12 Ratpheochromocytoma ATCC CRL-1721 NT Yes SH-SY5Y Human neuroblastoma ATCCCRL-2266 No NT SiMa Human neuroblastoma DSMZ ACC 164 Yes YesSK-N-BE(2)-C Human neuroblastoma ATCC CRL-2271 Yes NT SK-N-DZ Humanneuroblastoma ATCC CRL-2149 Yes NT SK-N-F1 Human neuroblastoma ATCCCRL-2142 No NT SK-N-SH Human neuroblastoma ECACC 86012802 No NT NT: Nottested. NDA: No detectable amount of SNAP-25 was deteced in this cellline.

Using a similar approach, cell lines comprising cells having cognatereceptors for other re-targeted endopeptidases can be assessed forretargeted endopeptidase uptake.

Example 2 Screening of Candidate Clonal Cell Lines EndogenousRe-Targeted Endopeptidase Receptor Expression

1. Single Dose Re-Targeted Endopeptidase Screening of Candidate ClonalCell Lines from a Parental SiMa Cell Line.

Companion patent application Zhu Hong et al., Cell Lines Useful inImmuno-Based Botulinum Toxin Serotype A Activity Assays, U.S. PatentApplication Ser. No. 61/160,199 discloses clonal cell lines derived froma parental SiMa cell line that were useful in a BoNT/A potency assay, asdescribed in Ester Fernandez-Salas, et al., Immuno-Based Botulinum ToxinSerotype A Activity Assays, U.S. patent application Ser. No. 12/403,531,each of which is hereby incorporated by reference in its entirety. Todetermine whether these clonal cell lines were able to uptake theappropriate re-targeted endopeptidase, each was screened using an ECLsandwich ELISA assay.

To prepare a lysate treated with a retarget endopeptidase, a suitabledensity of cells from a stock culture of the cell line being tested wasplated into the wells of 96-well tissue culture plates containing 100 μLof an appropriate serum growth medium (Table 1) overnight. The mediafrom the seeded cells was aspirated from each well and replaced withfresh media containing either 30 nM of a Noc/A retargeted endopeptidaseor 80 nM of a Dyn/A retargeted endopeptidase. After a 24 hourincubation, the cells were washed by aspirating the growth media andrinsing each well with 200 μL of 1×PBS. To harvest the cells, 1×PBS wasaspirated, the cells lysed by adding 30 μL of Lysis Buffer comprising 20mM Tris-HCl (pH 7.5), 150 mM NaCl, 1 mM EDTA, 1 mM EGTA, 1% Triton X-100to each well, and the plate incubated on a shaker rotating at 500 rpmfor 30 minutes at 4° C. The plate was centrifuged at 4000 rpm for 20minutes at 4° C. to pellet cellular debris and the supernatant wastransferred to a capture antibody coated 96-well plate to perform thedetection step.

To prepare an α-SNAP-25₁₉₇ capture antibody solution, the α-SNAP-25₁₉₇mouse monoclonal antibody contained in the ascites from hybridoma cellline 2E2A6 (Example XI) was purified using a standard Protein Apurification protocol.

To prepare an α-SNAP-25 detection antibody solution, α-SNAP-25 rabbitpolyclonal antibody S9684 (Sigma, St. Louis, Mo.) was conjugated toRuthenium(II)-tris-bipyridine-(4-methysulfonate) NHS ester labelingreagent (Meso Scale Discovery, Gaithersburg, Md.) according to themanufacturer's instructions (Meso Scale Discovery, Gaithersburg, Md.).The conjugation reaction was performed by adding to 30 μL of distilledwater reconstituted MSD SULFO-TAG™ stock solution to 200 μL of 2 mg/mLα-SNAP-25 polyclonal antibodies and incubating the reaction at roomtemperature for 2 hours in the dark. The labeled antibodies werepurified using a standard spin column protocol and the proteinconcentration determined using a standard colorimetric protein assay.The absorbance of the α-SNAP-25 antibody/MSD SULFO-TAG™ conjugate wasmeasured at 455 nm using a spectrophotometer to determine theconcentration in moles per liter. The detection antibody solution wasstored at 4° C. until needed. Long term storage of unused aliquots wasat −20° C.

To prepare an α-SNAP-25 solid phase support comprising an α-SNAP-25₁₉₇capture antibody, approximately 5 μL of the appropriate α-SNAP-25₁₉₇monoclonal antibody solution (20 μg/mL in 1×PBS) is added to each wellof a 96-well MSD High Bind plate and the solution is allowed to air dryin a biological safety cabinet for 2-3 hours in order to liquidevaporate the solution. Blocked plates were sealed and stored at 4° C.until needed.

To detect the presence of a cleaved SNAP-25 product by ECL sandwichELISA, the capture antibody-bound wells were then blocked by adding 150μL of Blocking Buffer comprising 2% Amersham Blocking Reagent (GE LifeSciences, Piscataway, N.J.) and 10% goat serum (VWR, West Chester, Pa.)at room temperature for 2 hours. The Blocking Buffer was aspirated, 25μL of a lysate from cells treated with re-targeted endopeptidase wasadded to each well and the plates were incubated at 4° C. for overnight.Plate wells were washed three times by aspirating the cell lysate andrinsing each well three times with 200 μL 1×PBS, 0.1% TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate). After washing, 25 μL of 5μg/mL α-SNAP-25 detection antibody solution comprising 2% AmershamBlocking Reagent in 1×PBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitanmonolaureate) was added to each well, sealed, and incubated at roomtemperature for 1 hour with shaking. After α-SNAP-25 detection antibodyincubation, the wells were washed three times with 200 μL 1×PBS, 0.1%TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate). After washing150 μL of 1× Read Buffer (Meso Scale Discovery, Gaithersburg, Md.) wasadded to each well and the plates were read using a SECTOR™ Imager 6000Image Reader (Meso Scale Discovery, Gaithersburg, Md.). The raw data wascollected using the ECL imager.

The results indicate that the parental SiMa cell line as well as clonalcell line H10 showed good uptake of the Noc/A retargeted endopeptidase(Table 4). In addition, these results reveal that many cell linesexhibited uptake of the Dyn/A retargeted endopeptidase (Table 4). Threeclonal cell lines (1E11, AF4, and DC4) showed good uptake of the Dyn/Aretargeted endopeptidase; eleven clonal cell lines (1E3, 2D2, 2D6, 3D8,5C10, 5F3, BB10, BFB, CG8, CG10, and DE7) exhibited moderate uptake ofthe Dyn/A retargeted endopeptidase; and (3B8, 2B9, CE6, YB8, 4C8, 2F5,AC9, CD6, DD10, YF5) showed minimal uptake of the Dyn/A retargetedendopeptidase. Some of these candidate cell lines were tested in a fulldose-response assay with the corresponding retargeted endopeptidase.

TABLE 4 Single-Dose Screening of Candidate Clonal Cell Lines Using Re-targeted Noc/A and Dyn/A Cell Line 30 nM Noc/A Uptake 80 nM Dyn/A UptakeAGN P33 +++ NT A10 − NT D11 − NT H1 − − H10 +++ − 1D4 NT − 2E4 NT − 3D5NT − 3G10 NT − 4D3 NT − BB3 NT − CC11 NT − DF5 NT − YB7 NT − BE3 NT −4B5 NT − 2B9 NT + 2F5 NT + 3B8 NT + 4C8 NT + AC9 NT + CD6 NT + CE6 NT +DD10 NT + YB8 NT + YF5 NT + 1E3 NT ++ 2D2 NT ++ 2D6 NT ++ 3D8 NT ++ 5C10NT ++ 5F3 NT ++ BF8 NT ++ BB10 NT ++ CG8 NT ++ CG10 NT ++ DE7 NT ++ 1E11NT +++ AF4 NT +++ DC4 NT +++ NT: Not Tested −: no uptake; +: minimaluptake; ++: moderate uptake; +++: good uptake

2. Full Dose Response Screening of Candidate Cell Lines.

Established cell lines identified above, were subsequently evaluatedusing a full dose response of the appropriate re-targeted endopeptidase.Cells from the different cell lines were plated in 96-well plates andexposed to various concentrations of Noc/A (0, 0.14 nM, 0.4 nM, 1.23 nM,3.7 nM, 11.1 nM, 33.3 nM, and 100 nM) or of Dyn/A (0.017 nM, 0.05 nM,0.15 nM, 0.45 nM, 1.4 nM, 4.1 nM, 12 nM, 37 nM, 111 nM, 333 nM, and 1000nM) for 24 hours. Retargeted endopeptidase-containing medium was thenremoved and replaced with fresh complete medium. Plates were incubatedanother 24 hours under 5% CO₂ at 37° C. to allow for the cleavage ofSNAP-25. Cells were lysed in the lysis buffer (Table 5) and platescentrifuged to eliminate debris. The lysates were used either in aWestern blot assay or in a sandwich ELISA.

For the Western blot analysis, samples were assayed for the presence ofboth the intact SNAP-25 and the SNAP-25 cleavage product as described inExample I.

For the sandwich ELISA, ELISA plates coated with 2E2A6 monoclonalantibody were blocked with 150 μL Blocking Buffer at room temperaturefor 2 hours. After blocking buffer was removed, 25 μL of cell lysate wasadded to each well and the plates were incubated at 4° C. for 2 hours.Plates were washed three times with PBS-T and 25 μL of SULFO-TAGNHS-Ester labeled detection anti-SNAP25 pAb antibody at 5 μg/mL in 2%blocking reagent in PBS-T was added to the bottom corner of wells. Theplates were sealed and shaken at room temperature for 1 hour, followedby three washes with PBS-T. After washes were completed, 150 μL of 1×Read Buffer per well was added and the plate was read in the SI6000Image reader. To determine the sensitivity of each one of the cell linestested, and EC₅₀ value was calculated for each cell line. The values forthe Noc/A retargeted endopeptidase are summarized in Table 5. Full doseresponse of retargeted endopeptidase Dyn/A were only performed in PC12and clone AF4. In both cases the assay did not reach an upper asymptoteand an EC₅₀ could not be calculated. The lower dose that produced asignal for the AF4 clone was 12 nM for both cell lines.

TABLE 5 Full-Dose Screening of Candidate Cell Lines Using RetargetedNoc/A and Dyn/A EC₅₀ EC₅₀ Noc/A Dyn/A Cell Line Description SourceUptake Uptake AGN P33 Human neuroblastoma —  5-10 nM NT BE(2)-C Humanneuroblastoma ATCC CRL-2268 NT NT N18TG2 Mouse neuroblastoma DSMZ ACC103 NT NT N18 Mouse Neuroblastoma ECACC 88112301 >100 nM NT ND3 Mouseneuroblastoma/primary neonatal ECACC 92090901 NDA NT rat DRG hybridND7/23 Mouse neuroblastoma/primary rat DRG ECACC 92090903 >100 nM NThybrid ND8 Mouse neuroblastoma/primary neonatal ECACC 92090904 NDA NTrat DRG hybrid ND15 Mouse neuroblastoma/primary neonatal ECACC92090907 >100 nM NT rat DRG hybrid Neuro-2a Mouse neuroblastoma ATCCCCL-131  30 nM NT NG108-15 Mouse neuroblastoma/rat glioma hybrid ECACC88112302 NT NT PC12 Rat pheochromocytoma ATCC CRL-1721 NT >1000 nMSH-SY5Y Human neuroblastoma ATCC CRL-2266 NT NT SiMa Human neuroblastomaDSMZ ACC 164  30 nM NT SiMa clone AF4 Human neuroblastoma — NT  >300 nMSiMa clone H1 Human neuroblastoma — >100 nM NT SiMa clone H10 Humanneuroblastoma —  20 nM NT SK-N-BE(2)-C Human neuroblastoma ATCC CRL-2271NT NT SK-N-DZ Human neuroblastoma ATCC CRL-2149 0.5-2 nM NT SK-N-F1Human neuroblastoma ATCC CRL-2142 >100 nM NT SK-N-SH Human neuroblastomaECACC 86012802 >100 nM NT NT: Not tested. NDA: No detectable amount ofSNAP-25 was deteced in this cell line.

Using a similar approach, clonal cell lines comprising cells havingcognate receptors for other re-targeted endopeptidases can be screenedand assessed for retargeted endopeptidase uptake.

Example 3 Evaluation of Growth Conditions on Retargeted EndopeptidaseUptake in Candidate Cell Lines

The following example illustrates how to determine culture conditions,growth and differentiation, for established cell lines that maximizere-targeted endopeptidase uptake.

1. Effects of Cell Differentiation and Trophic Factors on Re-TargetedEndopeptidase Uptake of Candidate Cell Lines.

To determine whether cell differentiation or the present of trophicfactors in the growth media improved re-targeted endopeptidase uptake,cell lines exhibiting good uptake of Noc/A were tested with differentmedia compositions. A suitable density of cells from a stock culture ofthe SiMa P>30 cell line being tested was plated into the wells of96-well tissue culture plates containing 100 μL of a serum-free mediumcontaining RPMI1640, 1% Penicillin-Streptomycin, 2 mM L-Glutamine,supplemented with B27, and N2, or 100 μL of a serum-free mediumcontaining RPMI1640, 1% Penicillin-Streptomycin, 2 mM L-Glutamine,supplemented with B27, N2, and NGF (Nerve Growth Factor, 100 ng/mL).These cells were incubated in a 37° C. incubator under 5% carbon dioxideuntil the cells differentiated, as assessed by standard and routinemorphological criteria, such as growth arrest and neurite extension(approximately 1 to 2 days). As a control, a suitable density of cellsfrom a stock culture of the cell line being tested was plated into thewells of 96-well tissue culture plates containing 100 μL of anappropriate growth medium (Table 1) without or with NGF (100 ng/mL).These undifferentiated control cells were grown in a 37° C. incubatorunder 5% carbon dioxide until cells reach the desired density(approximately 18 to 24 hours). The media from both differentiated andundifferentiated control cultures was aspirated from each well andreplaced with fresh media containing either 0 (untreated sample) or tovarious concentrations of Noc/A (0.14, 0.4, 1.23, 3.7, 11.1, 33.3, and100 nM). After a 24 hours treatment, the cells were washed and incubatedfor 24 hours in retargeted endopeptidase-free media in order to increasethe amount of SNAP25₁₉₇ produced. Cells were then washed and harvestedfor the ECL sandwich ELISA assay as described in Example II.

Effects of trophic factors were also tested on the SK-N-DZ cell line.SK-N-DZ cells were plated on a poly-D-lysine coated 96-well plate at25,000 cells per well in eight different SM media (Table 6) for 72hours. Cells were treated in the same eight media with Noc/A at doses of0, 0.3 nM, 3 nM, and 30 nM. After a 24 hour treatment, the cells werewashed and incubated for 24 hours n retargeted endopeptidase-free mediain order to increase the amount of SNAP-25₁₉₇ cleavage product produced.Cells were then washed and harvested for the Western blot assay asdescribed in Example I.

Differentiation did not have an effect on Noc/A uptake in the SiMa >P30cell line while it seemed to improve uptake in the SK-N-DZ cell line.The basal media had a significant effect on Noc/A uptake in the SK-N-DZcell line with RPMI1640 comprising trophic factors N2 and B27 being thebest combination. The presence of NGF in the media did not seem toimprove uptake in the two cell lines tested.

TABLE 6 Effects of Trophic Factors and Cell Differentiation on Noc/AUptake of Candidate Cell Lines. EC₅₀ Noc/A Uptake UndifferentiatedDifferentiated AGN P33 SK-N-DZ DMEM, 10% FBS — NT >30 nM  DMEM, 10% FBS,N2, B27 — NT 3 nM DMEM, 10% FBS, N2, — NT 3 nM B27, NGF DMEM, 10% FBS,N2, — NT >30 nM  B27, RA RPMI1640, 10% FBS — NT 10 nM  RPMI1640, 10%FBS, N2, B27 — 7.2 nM 1 nM RPMI1640, 10% FBS, N2, B27, — 9.1 nM 1 nM NGFRPMI1640, 10% FBS, N2, — NT 10 nM  B27, RA — RPMI1640, 10.2 nM  1 nM N2,B27 — RPMI1640, 9.8 nM 0.6 nM   N2, B27, NGF NGF: Nerve Growth Factor;RA: Retinoic Acid NT: Not tested

Using a similar approach, the growth and differentiation conditions forclonal cell lines comprising cells having cognate receptors for otherre-targeted endopeptidases can be assessed.

Example 4 Development of Established Cell Lines Expressing ExogenousRe-Targeted Endopeptidase Receptors

The following example illustrates how to make an established cell lineexpressing an exogenous receptor for a re-targeted endopeptidase.

1. Transfection of Target Receptor into Cells Comprising a CandidateCell Line.

The re-targeted endopeptidase Noc/A comprises the nociceptin targetingdomain which is the natural ligand of Opioid Receptor Like-1 (ORL-1). Toobtain an expression construst comprising an open reading frame for anORL-1, the expression contruct pReceiver-MO2/ORL-1 was obtained fromGeneCopoeia (GeneCopoeia, Germantown, Md.).

Alternatively, a polynucleotide molecule based on an ORL-1 amino acidsequence (e.g., the amino acid sequences SEQ ID NO:25 or SEQ ID NO:26)can be synthesized using standard procedures (BlueHeron® Biotechnology,Bothell, Wash.). Oligonucleotides of 20 to 50 bases in length aresynthesized using standard phosphoramidite synthesis. Theseoligonucleotides will be hybridized into double stranded duplexes thatare ligated together to assemble the full-length polynucleotidemolecule. This polynucleotide molecule will be cloned using standardmolecular biology methods into a pUCBHB1 vector at the SmaI site togenerate pUCBHB1/ORL-1. The synthesized polynucleotide molecule isverified by sequencing using Big Dye Terminator™ Chemistry 3.1 (AppliedBiosystems, Foster City, Calif.) and an ABI 3100 sequencer (AppliedBiosystems, Foster City, Calif.). If desired, an expression optimizedpolynucleotide molecule based on an ORL-1 amino acid sequence (e.g., theamino acid sequences SEQ ID NO:25 or SEQ ID NO:26) can be synthesized inorder to improve expression in an Escherichia coli strain. Thepolynucleotide molecule encoding the ORL-1 can be modified to 1) containsynonymous codons typically present in native polynucleotide moleculesof an Escherichia coli strain; 2) contain a G+C content that moreclosely matches the average G+C content of native polynucleotidemolecules found in an Escherichia coli strain; 3) reducepolymononucleotide regions found within the polynucleotide molecule;and/or 4) eliminate internal regulatory or structural sites found withinthe polynucleotide molecule, see, e.g., Lance E. Steward et al.,Optimizing Expression of Active Botulinum Toxin Type A, U.S. PatentPublication 2008/0057575 (Mar. 6, 2008); and Lance E. Steward et al.,Optimizing Expression of Active Botulinum Toxin Type E, U.S. PatentPublication 2008/0138893 (Jun. 12, 2008). Once sequence optimization iscomplete, oligonucleotides of 20 to 50 bases in length are synthesizedusing standard phosphoramidite synthesis. These oligonucleotides arehybridized into double stranded duplexes that are ligated together toassemble the full-length polynucleotide molecule. This polynucleotidemolecule is cloned using standard molecular biology methods into apUCBHB1 vector at the SmaI site to generate pUCBHB1/ORL-1. Thesynthesized polynucleotide molecule is verified by DNA sequencing. If sodesired, expression optimization to a different organism, such as, e.g.,a yeast strain, an insect cell-line or a mammalian cell line, can bedone, see, e.g., Steward, U.S. Patent Publication 2008/0057575, supra,(2008); and Steward, U.S. Patent Publication 2008/0138893, supra,(2008). Exemplary polynucleotide molecules encoding an ORL-1 include SEQID NO:61 and SEQ ID NO:62.

To construct an expression construct encoding an ORL-1, a pUCBHB1/ORL-1construct will be digested with restriction endonucleases that 1)excised the polynucleotide molecule encoding the open reading frame ofORL-1; and 2) enabled this polynucleotide molecule to be operably-linkedto a pcDNA3 vector (Invitrogen, Inc., Carlsbad, Calif.). This insertwill be subcloned using a T4 DNA ligase procedure into a pcDNA3 vectorthat will be digested with appropriate restriction endonucleases toyield pcDNA3/ORL-1. The ligation mixture will be transformed intoelectro-competent E. coli BL21(DE3) cells (Edge Biosystems, Gaitherburg,Md.) using an electroporation method, and the cells will be plated on1.5% Luria-Bertani agar plates (pH 7.0) containing 50 μg/mL ofampicillin, and will be placed in a 37° C. incubator for overnightgrowth. Bacteria containing expression constructs will be identified asampicillin resistant colonies. Candidate constructs will be isolatedusing an alkaline lysis plasmid mini-preparation procedure and will beanalyzed by restriction endonuclease digest mapping to determine thepresence and orientation of the insert. This cloning strategy willyielded a pcDNA3 expression construct comprising the polynucleotidemolecule encoding an ORL-1.

The re-targeted endopeptidase Dyn/A comprises the dynorphin targetingdomain which is the natural ligand of κ-opioid receptor (KOR). To obtainan expression construst comprising an open reading frame for an ORL-1,the expression contruct pReceiver-MO2/KOR-1 was obtained fromGeneCopoeia (GeneCopoeia, Germantown, Md.). Alternatively, expressioncontructs encoding the KOR can be synthesized and subcloned using anapproach similar to the one described above to produce the expressioncontruct pcDNA3.1/KOR. Exemplary KOR amino acid sequences include SEQ IDNO:29 and SEQ ID NO:30; exemplary polynucleotide molecules encoding aKOR include SEQ ID NO:65 and SEQ ID NO:66.

Similar cloning strategies can be used to make expression constructsencoding other re-target endopeptidase receptors, such as, e.g.,pcDNA3.1/DOR or pcDNA3.1/MOR, pcDNA3.1/Galanin receptor 1,pcDNA3.1/Galanin receptor 2, or pcDNA3.1/Galanin receptor 3. ExemplaryDOR amino acid sequences include SEQ ID NO:27 and SEQ ID NO:28;exemplary MOR amino acid sequences include SEQ ID NO:31 exemplaryGalanin receptor 1 amino acid sequences include SEQ ID NO:136, SEQ IDNO:137, and SEQ ID NO:138; exemplary Galanin receptor 2 amino acidsequences include SEQ ID NO:139; and exemplary Galanin receptor 3 aminoacid sequences include SEQ ID NO:140. Exemplary polynucleotide moleculesencoding a DOR include SEQ ID NO:63 and SEQ ID NO:64; exemplarypolynucleotide molecules encoding a MOR include SEQ ID NO:67; exemplarypolynucleotide molecules encoding a Galanin receptor 1 include SEQ IDNO:141, SEQ ID NO:142, and SEQ ID NO:143; exemplary polynucleotidemolecules encoding a Galanin receptor 2 include SEQ ID NO:144; andexemplary polynucleotide molecules encoding a Galanin receptor 3 includeSEQ ID NO:145.

To introduce an expression construct encoding a re-targetedendopeptidase receptor, cell lines were transfected with an expressionconstruct encoding a re-targeted endopeptidase receptor. To transfect acell line with an opioid or opiod-like receptor, cells from a candidatecell line were seeded at a density of 1×10⁷ cells in a T₁₇₅ Collagen IVcoated flask and grown in a 37° C. incubator under 5% carbon dioxideuntil cells reach the desired density. A 4.2 mL transfection solution isprepared by adding 4 mL of OPTI-MEM Reduced Serum Medium containing 200μL of LipofectAmine 2000 (Invitrogen, Carlsbad, Calif.) incubated atroom temperature for 5 minutes to 4 mL of OPTI-MEM Reduced Serum Mediumcontaining 20 μg of a pReceiver-MO2/ORL-1 or 20 μg ofpReceiver-MO2/KOR-1. This transfection was incubated at room temperaturefor approximately 20 minutes. The media was replaced with 8 mL of freshserum-free and antibiotic-free media and the transfection solution wasadded to the cells. The cells were then incubated in a 37° C. incubatorunder 5% carbon dioxide for approximately 16-18 hours. Transfectionmedia was replaced with fresh growth media and incubate cells in a 37°C. incubator under 5% carbon dioxide. After 24 hours, the growth mediawere replaced with fresh growth media containing the antibiotic G418 at1 mg/mL in the culture medium (selection medium) and cells wereincubated for 7 days. The selection medium was changed every week for atotal of 4 weeks (about 90% cells died and were removed during theweekly media changes).

Candidate cell lines transfected with the ORL-1 receptor includedSiMa >P30, ND15, ND7, NG108-T15 and SK-N-DZ cell lines. Candidate celllines transfected with the KOR-1 receptor included SiMa, SiMa >P30,ND15, ND7, NG108-T15 and SK-N-DZ cell lines. Transfected NG108-T15 cellsdid not survive selection in G418.

2. Single Dose and Dose Response Screening of Stable Transfected CellLines Using Re-Targeted Endopeptidase Molecules.

Cells from the transfected and selected candidate cell lines from theprevious section were plated on 96-well poly-D-lysine or Collagen IVcoated plates at 1×10⁵ cells/well in medium RPMI1640 containing N2 andB27 supplements, and NGF (50-100 ng/ml) for 20±4 hours before compoundtreatment. Then the cells stably transfected with the ORL-1 receptorwere treated with re-targeted endopeptidase Noc/A at 30 nM in the samemedium for 24±2 hours, except for the SK-N-DZ cell line that was treatedat 10 nM. Cells were lysed in 120 μL lysis buffer, and 20 μL of thelysate was mixed with the 2×SDS buffer for the Western Blot assay thatwas performed as detailed in Example I. All of the cells lines displayedincrease uptake of the re-targeted Noc/A compound when transfected withthe ORL-1 receptor (Table 7).

TABLE 7 Cell lines stably transfected with ORL-1 tested with re-targetedendopeptidase Noc/A % Cleaved SNAP25 at 30 nM Non- Cell line Descriptiontransfected Transfected AGN P33 Human Neuroblastoma 20% 40% SK-N-DZHuman Neuroblastoma 25% @ 10 nM 40% @ 10 nM ND7 Mouse Neuroblastoma 10%42% and rat DRG cells hybrid ND15 Mouse Neuroblastoma  8% 20% and ratDRG cells hybrid NG108- Mouse neuroblastoma/rat No cells No cellssurvive T15 glioma hybrid survive

Cells from the transfected and selected candidate cell lines from theprevious section were plated on 96-well poly-D-lysine or Collagen IVcoated plates at 1×10⁵ cells/well in medium RPMI1640 containing 10% FBSand N2 and B27 supplements for 20±4 hours before compound treatment. Thecells stably transfected with the KOR-1 receptor were treated withre-targeted endopeptidase Dyn/A at 100 nM in the same medium for 24±2hours. Cells were lysed in 120 μL lysis buffer, and 20 μL of the lysatewas mixed with the 2×SDS buffer for the Western Blot assay that wasperformed as detailed in Example I. All of the cells lines displayedincrease uptake of the re-targeted Dyn/A compound when transfected withthe human KOR-1 receptor.

3. Selection of Stably Transfected Clonal Cell Lines Exhibiting HighSensitivity by Serial Dilution

The following example illustrates how to identify clonal cells from astably transfected established cell line that are susceptible tore-targeted endopeptidase action or have re-targeted endopeptidaseuptake capacity.

For single cell cloning of the selected cells described above, thelimited-dilution cell line cloning method was employed. Cells weretrypsinized, counted, diluted to achieve 0.5-1 cell per 100 μL, andplated on selection media in five poly-D-lysine coated 96-well plates at100 μL per well. Cells were incubated for more than 2 weeks untilcolonies formed on the bottom of the well. The positive coloniesoriginating from single cells were marked. Pictures of single-cellderived clones were taken using a microscope camera. Cells from wellswith single clones were grown for an additional week and transferredinto 24 well plates about 4 weeks after cloning started.

For clone selection, the main parameter used to screen for positiveclones was the highest amount of SNAP-25 cleavage obtained after Noc/Aor Dyn/A treatment measured using the Western Blot analysis with theantibody that recognizes both intact and cleaved SNAP-25. Clonesoverexpressing ORL-1 were tested with 10 nM and 30 nM re-targetedendopeptidase Noc/A overnight as soon as enough cells became available(Table 8). Clones overexpressing KOR-1 were tested with 100 nMre-targeted endopeptidase Dyn/A overnight (Table 9). In addition, clonesoverexpressing KOR-1 were tested on the Dynorphin binding assay asdescribed in Example I.

TABLE 8 Single-Dose Screening of Candidate Clonal Cell Lines Stablytransfected with ORL-1 Using re-targeted endopeptidase Noc/A Second 30nM screening 10 nM Noc/A Noc/A @ 1 nM Cell Line Clone number UptakeUptake (% cleaved) AGN P33 1 + + 28% AGN P33 2 ++ +++ 50% AGN P33 3 − +NT AGN P33 4 ND ND NT AGN P33 5 − + 31% AGN P33 6 ++ +++ 60% AGN P337 + + 14% AGN P33 8 + + NT AGN P33 9 + + 38% AGN P33 10 + ++ 29% AGN P3311 + + NT AGN P33 12 + + 27% ND7 1C11 NT ++ NT ND7 2F3 NT − NT ND7 1D10NT − NT ND7 1F9 NT − NT ND7 1G10 NT − NT ND7 2D8 NT − NT ND7 2E2 NT − NTND7 4B7 NT +++ NT ND7 3C11 NT − NT ND7 3C3 NT + NT ND7 3E8 NT − NT ND73E11 NT − NT ND7 2G3 NT − NT ND7 4D5 NT + NT ND7 4D8 NT + NT ND7 4C8 NT− NT ND7 4C9 NT +++ NT ND7 4E8 NT + NT ND7 2E6 NT ++ NT ND7 4F4 NT +++NT ND7 5D6 NT − NT ND7 5G3 NT − NT ND7 4D5 NT ++ NT ND15 1C10 NT + NTND15 1F10 NT ++ NT ND15 2D8 NT ++ NT ND15 2E11 NT − NT ND15 2F4 NT ++ NTND15 2F10 NT ++ NT ND15 2F11 NT − NT ND15 3C4 NT + NT ND15 3C7 NT ++ NTND15 3E8 NT +++ NT ND15 4C8 NT + NT ND15 4D8 NT + NT SK-N-DZ #2 − − NTSK-N-DZ #4 − − NT SK-N-DZ #5 +++ ++ NT SK-N-DZ #6 NT ++ NT SK-N-DZ #7 +NT NT SK-N-DZ #8 − NT NT SK-N-DZ #9 + NT NT SK-N-DZ #10 − NT NT SK-N-DZ#11 + +++ NT SK-N-DZ #12 − NT NT SK-N-DZ #14 ++ NT NT SK-N-DZ #16 − NTNT SK-N-DZ #17 + +++ NT SK-N-DZ #19 + +++ NT SK-N-DZ #20 − NT NT SK-N-DZ#23 NT ++ NT SK-N-DZ #25 − NT NT SK-N-DZ #26 − ++ NT SK-N-DZ #27 + NT NTSK-N-DZ #28 ++ + NT SK-N-DZ #30 ++ NT NT SK-N-DZ #31 − NT NT SK-N-DZ #32++ ++ NT SK-N-DZ #33 + NT NT SK-N-DZ #34 +++ ND NT SK-N-DZ #35 + ++ NTSK-N-DZ #36 − NT NT SK-N-DZ #37 +++ ++ NT SK-N-DZ #42 − NT NT SK-N-DZ#43 + ++ NT ND: Not Determined; NT: Not Tested. −: no uptake; +: minimaluptake; ++: moderate uptake; +++: good uptake

TABLE 9 Single-Dose Screening of Candidate Clonal Cell Lines Stablytransfected with KOR-1 Using re-targeted endopeptidase Dyn/A Clone 100nM Dyn/A 100 nM Dyn Selected future Cell Line number Uptake bindingtesting SiMa 2 − − No SiMa 6 + + No SiMa 8 + + No SiMa 12 +++ ++ YesSiMa 14 ++ ++ No SiMa 20 + ++ No SiMa 25 ++ ++ No AGN P33 1 +++ + YesAGN P33 3 ++ + No AGN P33 5 ++ + Yes AGN P33 6 ++ + No AGN P33 7 +++ +Yes AGN P33 8 ++ + Yes AGN P33 9 +++ + Yes AGN P33 10 +++ + Yes AGN P3311 ++ + No AGN P33 12 +++ + Yes AGN P33 14 + + No AGN P33 16 ++ + No AGNP33 17 +++ + Yes AGN P33 21 + ++ No ND7 A1 + + No ND7 A2 − − No ND7 A3 −− No ND7 A4 − − No ND7 A5 − − No ND7 A6 − − No ND7 A7 − − No ND7 A8 − −No ND7 A9 − − No ND7 A10 − − No ND7 A11 − − No ND7 A12 +++ +++ Yes ND7B1 − − No ND7 B2 − − No ND7 B3 − − No ND7 B4 − − No ND7 B5 + + Yes ND7B6 − − No ND7 B7 − − No ND7 B8 − − No ND7 B9 − − No ND7 B10 − − No ND7B11 − − No ND7 B12 − − No ND7 C1 − − No ND7 C2 − − No ND7 C3 − − No ND7C4 − − No ND7 C5 − − No ND7 C6 + + No ND7 C7 − − No ND7 C8 − − No ND7 C9− − No ND7 C10 − − No ND7 C11 − − No ND7 C12 − − No ND7 D1 − − No ND7 D2− − No ND7 D3 − − No ND7 D4 − − No ND7 D5 − − No ND7 D6 ++ ++ Yes ND7 D7++ ++ Yes ND7 D8 − − No ND7 D9 − − No ND7 D10 − − No ND7 D11 − − No ND7D12 − − No ND7 E1 − − No ND7 E2 − − No ND7 E3 − − No ND7 E4 − − No ND7E5 − − No ND7 E6 − − No ND7 E7 − − No ND7 E8 − − No ND7 E9 − − No ND7E10 − − No ND7 E11 − − No ND7 E12 ++ ++ Yes ND7 F1 − − No ND7 F2 − − NoND7 F3 − − No ND7 F4 − − No ND15 A1 − − No ND15 A2 − − No ND15 A3 + − NoND15 A4 + − No ND15 A5 − − No ND15 A6 ++ − No ND15 A7 ++ − No ND15 A8 ++− No ND15 A9 + − No ND15 A10 + − No ND15 A11 − − No ND15 A12 − − No ND15B1 − − No ND15 B2 ++ − No ND15 B3 − − No ND15 B4 − − No ND15 B5 +++ −Yes ND15 B6 + − No ND15 B7 − − No ND15 B8 − − No ND15 B9 − − No ND15 B10− − No ND15 B11 − − No ND15 B12 − − No ND15 C1 − − No ND15 C2 +++ + YesND15 C3 − − No ND15 C4 − − No ND15 C5 + NT No ND15 C6 +++ NT Yes SK-N-DZ#11 NT NT ND ND: Not Determined; NT: Not Tested. −: no uptake; +:minimal uptake; ++: moderate uptake; +++: good uptake

4. Dose Response Screening of Stably Transfected Clonal Cell Lines UsingRe-Targeted Endopeptidase.

Candidate stably transfected clonal cell lines from section 3 showinggood uptake of the re-targeted endopeptidase Noc/A were tested in fulldose response experiments to determine sensitivity and efficacy towardsthe re-targeted endopeptidase Noc/A. Cells were plated on 96-wellpoly-D-lysine or Collagen IV coated plates at 1×10⁵ cells/well in mediumRPMI1640 containing N2 and B27 supplements, and NGF (50-100 ng/mL) for20±4 hours before compound treatment. Cells from the parental AGN P33cell line and the ND7 clonal cell lines were treated with 0, 0.14 nM,0.4 nM, 1.23 nM, 3.7 nM, 11.1 nM, 33.3 nM, and 100 nM of Noc/A in thesame medium for 24 hours plus 24 hours incubation in re-targetedendopeptidase free media to allow for cleavage of SNAP-25. Cells fromthe parental AGN P33 cell line were also treated with 0, 0.03 nM, 0.08nM, 0.24 nM, 0.74 nM, 2.22 nM, 6.67 nM, and 20 nM of Noc/A in the samemedium for 24 hours plus 24 hours incubation in re-targetedendopeptidase free media to allow for cleavage of SNAP-25. Media wasremoved and cells washed and lysed for the ECL sandwich ELISA assay asdetailed in Example II. The data from the AGN P33 parental and theclonal cell lines stably transfected with the ORL-1 receptor issummarized in Table 10. Clones #2 and #6 demonstrated better sensitivityand efficacy towards the re-targeted endopeptidase Noc/A than theparental cell line. Moreover, the increased sensitivity of the newclonal cell lines allowed the use of lower concentrations for thedose-response confirming the new clonal cell lines are more sensitive.

TABLE 10 Summary table of signal-to-noise ratios (S/N) and EC₅₀ valuesof the three most sensitive clones overexpressing ORL-1 in the AGN P33background cell line. Parental Clone 2 Clone 6 Clone 8 S/N Ratio 0.03nM/BK 41 26 1.8 S/N Ratio 20 nM/BK 259 522 33.1 S/N Ratio 0.14 nM/BK S/NRatio 100 nM/BK EC₅₀ (nM) 6.8 ± 1.1 0.6 ± 0.1 0.7 ± 0.07 0.3 ± 0.2

The data from the ND7 parental and the clonal cell lines stablytransfected with the ORL-1 receptor is summarized in Table 11. All theclones tested demonstrated improved sensitivity and efficacy towards there-targeted endopeptidase Noc/A than the parental cell line ND7. Clones4B7, 1E6, and 1C11 were the most sensitive with EC₅₀ values lower than10 μM.

TABLE 11 Summary table of signal-to-noise ratios (S/N) and EC₅₀ valuesof the six most sensitive clones overexpressing ORL-1 in the ND7background cell line. Parental 1C11 4B7 4C9 4F4 1E6 3E9 S/N Ratio 1.79.3 11.1 5.3 3.6 5.8 5.1 0.14 nM/BK S/N Ratio 53 217 243 126 169 123 121100 nM/BK EC₅₀ (nM) >50 8.6 ± 5.7 ± 33 ± 24 ± 6.7 ± >30 nM 2 0.5 11 5 1

Table 12 summarizes the results obtained with the generation and testingof clonal cell lines overexpressing the ORL-1 receptor in different cellbackgrounds.

TABLE 12 Summary of clonal cell lines overexpressing the Human ORL-1receptor tested with Noc/A Stable cell lines Background tested with CellLine Species full dose of Noc/A EC₅₀ (nM) AGN P33 Human neuroblastomaThree 0.6-2.5 ND7 Rat neuroblastoma Six 3.7-8   and DRG hybrid SK-N-DZHuman neuroblastoma None (seven N/A stable clones selected for furtherstudies)

Example 5 Development of Clonal Cell Lines from a Parental SK-N-DZ CellLine

The following example illustrates how to identify clonal cells from aparental established cell line that are susceptible to re-targetedendopeptidase inhibition of exocytosis or have re-targeted endopeptidaseuptake capacity.

1. Isolation of Clonal Cell Lines.

During characterization of the SK-N-DZ cell line, it was discovered thatthe cells comprising this established cell line comprised at least fivedifferent cellular phenotypes. To determine whether any one of thesephenotypically-distinct cell types was responsible for thesusceptibility of this cell line to re-targeted endopeptidase inhibitionof exocytosis, two different limited-dilution screens were conducted toobtain single colony isolates for each phenotypically-distinct celltype.

A suitable density of cells from a SK-N-DZ stock were grown in DMEM, 10%Fetal Bovine Serum (heat-inactivated), 0.1 mM Non-Essential Amino-Acids,10 mM HEPES, 1 mM Sodium Pyruvate, 100 U/ml Penicillin, 100 μg/mlStreptomycin, contained in a T175 Collagen IV coated flask. After thesecond passage, the cells were trypsin-treated to produce a cellsuspension and the cell concentration was determined. About 4.0×10⁶cells from this cell suspension was transferred into a 50 mL tube andthe cells were dissociated into single cells by repeated vigorousexpulsion through an 18.5 gauge needle using a 10 mL syringe. Cells fromthis disassociated single-cell suspension were then diluted to aconcentration of 0.2×10⁶ cells/mL by adding 15 mL of fresh growthmedium, and 2.5 μL of this dilution was added to 50 mL of fresh growthmedium to obtain a concentration of 10 cells/mL. From this finaldilution stock, 100 μL of growth medium was added to each well of a96-well Collagen IV coated plates and the cells were grown undisturbedin a 37° C. incubator under 5% carbon dioxide for four weeks. Four96-well plates were setup for analysis. After four weeks, each well wasmicroscopically examined to identify growing single colonies, and foreach colony identified 100 μL of fresh growth medium was added to eachwell and the cells were grown undisturbed in a 37° C. incubator under 5%carbon dioxide for two weeks. After two additional weeks of growth, thegrowing single colonies were trypsin-treated and transferred to a new96-well plate for continued growth. Once colonies grew to about 1,000cells, based on visual inspection, the cells were trypsin-treated andeach cell-suspension was transferred into a new well from a 24-wellCollagen IV-coated plate. The cells were grown in a 37° C. incubatorunder 5% carbon dioxide with fresh growth medium being replenished every2-3 days, if needed. The cells were grown until the culture reachedapproximately 60% confluence or greater, at which point the cells weretrypsin-treated and each cell-suspension was transferred into a 25 cm²Collagen IV-coated flask, based on the confluence of the cells in the24-well plate. The cells were grown in a 37° C. incubator under 5%carbon dioxide with fresh growth medium being replenished every 2-3days, if needed. Once the cells in the flask reached 70-80% confluence,they were frozen and stored in liquid nitrogen until the clonal celllines were tested to determine their susceptibility to Noc/A inhibitionof exocytosis. Of the 384 colony isolates initially setup from bothscreens, 24 clonal cell lines were selected based on viability andgrowth criteria and expanded for subsequent screening procedures. Ofthose, 12 fast growing cell lines were identified.

2. Primary Screen for Re-Targeted Endopeptidase Activity Susceptibilityof Cells from a Clonal Cell Line Using a Re-Targeted Endopeptidase.

To determine whether cells from a clonal cell line were susceptible tore-targeted endopeptidase Noc/A activity, a primary screen was conductedusing an immuno-based method for determining endopeptidase activity.

Thirteen SK-N-DZ clones (#3, #4, #5, #8, #9, #10, #13, #15, #16, #17,#18, #22, and #23) plus SK-N-DZ parental cells were plated on a 96-wellplate (unknown cell number per well) in EMEM, 10% FBS, 1×B27, and 1×N2and incubated over night. Cells were treated with 1 nM Noc/A for 24hours. Cells were lysed with 100 μL of lysis buffer for 20 minutes andcentrifuged at 4000 rpm for 20 minutes. Fifty microliters of 2×SDSSample buffer were added to 50 μL of cell lysate and heated at 95° C.for 5 minutes. Ten microliters of protein sample were loaded per lane on12% NuPage gels and a Western Blot assay was performed as described inExample I. Evaluation of the total SNAP-25 and the cleaved SNAP-25demonstrated that clones #3, #8, #15, and #22 were at least as good asparental cells for Noc/A uptake. Full dose response treatment andanalysis with the ECL sandwich ELISA assay was conducted after the cellswere scale up.

3. Secondary Response Screening of Clonal Cell Lines Using Re-TargetedEndopeptidase Molecule.

To determine whether cells from a clonal cell line were susceptible tore-targeted endopeptidase Noc/A activity, a secondary screen wasconducted using an immuno-based method for determining endopeptidaseactivity.

To further compare these SK-N-DZ cloned cell lines, the ECL sandwichELISA assay was carried out. Five clones (#3, #9, #15, #16, #22) plusSK-N-DZ parental cells were plated on one 96-well Poly-D-lysine coatedplate per cell line at 25,000 cells per well in RPMI 1640, 10% FBS,1×B27, and 1×N2 media (no NGF) over the weekend. Cells were treated withNoc/A at doses from 0 to 20 nM (0, 0.03, 0.08, 0.24, 0.74, 2.22, 6.67,20 nM) for 24 hours. The cleaved SNAP-25₁₉₇ was quantified with the ECLELISA assay as detailed in Example I.

Table 13 shows the EC₅₀ values and signal to noise for the five clonesand their parental cell line. Three clones named #3, #9, and #15generated lower EC₅₀ values (<1 nM) and clone #16 and #22 generatedsimilar EC₅₀ values when compared to the parental cell line (˜2 nM).However, the total signals from cleaved SNAP25 were higher in clones #3,#22, and the parental cells. Clones #9, #16, and #15 had lower totalsignals when compared to the rest of the cell lines.

TABLE 13 Summary table of signal-to-noise ratios (S/N) and EC₅₀ valuesof the five clones obtained from SK-N-DZ cells by limited-dilutioncloning. Parental 3 9 19 16 22 S/N Ratio 2 3 2 2 2 3 0.03 nM/BK S/NRatio 19 27 12 8 14 20 20 nM/BK EC₅₀ (nM) 2.6 ± 0.8 ± 0.7 ± 0.6 ± 2.2 ±1.9 ± 1.5 0.07 0.04 0.1 0.8 0.6

Conditions for Noc/A treatment on SK-N-DZ clones were optimized and anassay was run comparing clones #3, #15, and #22, and the parentalheterogeneous SK-N-DZ cell line. Table 14 shows the result of thecomparison and demonstrated that assay optimization has greatly improvedthe signal to noise for the assay. Clones #3 and #22 were selected forfurther assay development as they possess excellent sensitivity andefficacy.

TABLE 14 Summary table of signal-to-noise ratios (S/N) and EC₅₀ valuesof three clones obtained from SK-N-DZ cells using optimized conditions.Parental 3 15 22 S/N Ratio 0.03 nM/BK 15 8 5 10 S/N Ratio 20 nM/BK 10789 33 60 EC₅₀ (nM) 0.6 ± 0.2 0.9 ± 0.2 0.6 ± 0.1 0.4 ± 0.09

Example 6 Characterization and Comparison of Clonal Cell Lines forRe-Targeted Endopeptidase Uptake

The following example illustrates how to characterize and compare clonalcell lines originated either from an established cell line comprising aheterogeneous population or by transfection of the target receptor andsubsequent cloning of the cell line.

To evaluate the specificity or selectivity of re-targeted endopeptidaseuptake, non-specific uptake assays were performed using of a re-targetedendopeptidase lacking the targeting domain. For opioid re-targetedendopeptidase, cells from the AGN P33 clone #6 cell line (comprisingcells stably transformed with an expression construct encoding an ORL-1receptor) and the SK-N-DZ clonal cell lines #3 and #22 (comprising cellsthat express endogenous ORL-1 receptor) were seeded at 150,000 cells perwell on a 96-well Poly-D-lysine coated plate in RPMI 1640 serum freemedia containing N2 and B27 supplements, and NGF (50 ng/mL) andincubated for 20±4 hours at 37° C. in a 5% CO₂ incubator before compoundtreatment. Cells were treated with 8-doses of Noc/A ranging from 0-20 nMor 0-40 nM and or eight doses of LH_(N)/A ranging from 0 to 400 nM or 0to 40 nM in the same medium for 22 hours. Media was removed and cellswashed, lysed, and centrifuged to eliminate debris in preparation for asandwich ELISA assay. An ELISA plate coated with 2E2A6 monoclonalantibody was blocked with 150 μL Blocking Buffer at room temperature for1 hour. After blocking buffer was removed, 30 μL of cell lysate wasadded to each well and the plate was incubated at 4° C. for 2 hours.Plates were washed three times with PBS-T and 30 μL of SULFO-TAGNHS-Ester labeled detection α-SNAP25 polyclonal antibodies at 5 μg/mL in2% blocking reagent in PBS-T was added to the bottom corner of wells.The plate was sealed and shaken at room temperature for 1 hour, followedby three washes with PBS-T. After washes were completed, 150 μL of 1×Read Buffer per well was added and the plate was read in the SI6000Image reader. The results comparing Noc/A uptake relative to thenegative control LH_(N)/A are shown in Table 15 and Table 16. Theseresults indicate that there was good separation between Noc/A andLH_(N)/A uptake in both cell lines demonstrating specific uptake ofNoc/A.

TABLE 15 Non-specific uptake for SK-N-DZ clone #3. Summary of fourindependent experiments nM % non-specific uptake SEM (standard error ofthe mean) 0 2 0.5 1 6 0.5 2 8 0.5 5 10 1 15 19 0.9 44 33 1.5 133 65 2.4400 93 2.3

TABLE 16 Non-specific uptake for hORL-1 #6 cells. Summary of threeindependent experiments nM % non-specific uptake SEM (standard error ofthe mean) 0 1 0.2 1 2 0.2 2 3 0.6 5 3 0.3 15 8 1.3 44 12 1.9 133 22 3.0400 32 3.0

Table 17 summarizes the results for the characterization and comparisonof the three cell lines. SK-N-DZ clonal cell lines #3 and #22 possess asensitivity identical to the primary eDRG and an excellentsignal-to-noise to develop a robust assay for re-targeted endopeptidaseNoc/A. The AGN P33 clonal cell line #6 is also an excellent candidatewith low non-specific uptake and adequate sensitivity.

TABLE 17 Parameter SK-N-DZ clone 3 SK-N-DZ clone 22 AGN P33 clone 6 eDRGCell line species Human Clonal Human Clonal Human Clonal Rat primaryCell Receptor Human ORL1 Human ORL1 Human ORL1 Rat ORL1 Expressionendogenous endogenous transfected endogenous Dynamic Range 0.03 to 20 nMdose 0.03 to 20 nM 0.04 to 40 nM dose 0.17 to 20 nM dose response doseresponse response response Sensitivity (EC₅₀) EC₅₀ = 0.75 ± 0.1 EC₅₀ =0.8 ± 0.2 EC₅₀ = 2.4 ± 0.2 EC₅₀ = 0.8 ± 0.15 (N = 10) (N = 9) (N = 21)(N = 6) ULOQ 20 nM 20 nM 20 nM 10-20 nM S/N ULOQ/ 98 ± 15 (N = 10) 86 ±17 (N = 9) 385 ± 32 (N = 19) ~300 background S/N LLOQ/ 12 ± 2 (N = 11)10 ± 2 (N = 9) 29 ± 7 (N = 18) N/A background Specificity vs LH_(N)/A ≧2logs (N = 4) ≧2 logs (N = 4) ≧2 logs (N = 3) N/A SNAP-25 ExpressionEndogenous Endogenous Endogenous Endogenous Competition with Fullcompetition Full competition Partial competition N/A Nociceptin Var. (n= 4) (n = 4) (n = 4) Inhibition by Ab Anti- Full competition Fullcompetition Full competition N/A nociceptin (n = 4) (n = 4) (n = 4)Inhibition by Anti-868 Partial competition Partial competition Partialcompetition N/A Ab (N = 3) (N = 3) (N = 3)

To evaluate the sensitivity of re-targeted endopeptidase uptake, ligandsaturation binding assays were performed. The interaction of mostligands with their binding sites can be characterized in terms ofbinding affinity (NIH Assay Guidance). In general, high affinity bindinginvolves a longer residence time for the ligand at its receptor bindingsite than in the case of low affinity binding. The dissociation constantis commonly used to describe the affinity between a ligand (L) (such asa drug) and a protein (P) i.e. how tightly a ligand binds to aparticular protein. An equilibrium saturation binding experimentmeasures total and nonspecific binding (NSB) at various radioligandconcentrations. The equilibrium dissociation constant or affinity forthe radioligand, K_(d), and the maximal number of receptor bindingsites, Bmax, can be calculated from specific binding (total−NSB) usingnon-linear regression analysis. The K_(d) for the specific binding canbe calculated using a one-site binding hyperbola nonlinear regressionanalysis (i.e. GraphPad Prism) as shown in the equation below, whereBmax is the maximal number of binding sites (pmol/mg, or pmol/cells, orsites/cells), and K_(d) (nM, pM, etc.) is the concentration ofradioligand required to reach half-maximal binding:

${Bound} = \frac{B_{\max} \times \lbrack L\rbrack}{\lbrack L\rbrack + K_{d}}$

For opioid re-targeted endopeptidase, cells from the AGN P33 clone #6cell line (comprising cells stably transformed with an expressionconstruct encoding an ORL-1 receptor), the SK-N-DZ parental cell line,and the SK-N-DZ clonal cell lines #3, #15, and #22 (comprising cellsthat express endogenous ORL-1 receptor) were plated at 200,000 cells perwell on a 48-well Poly-D-lysine coated plate in RPMI 1640 serum freemedia containing 1×N2 and 1×B27 supplements and incubated overnight at37° C. in a 5% CO₂ incubator. Media was removed and cells and 150 μL ofTris binding buffer was added to wells used to assess total binding and100 μL of Tris binding buffer was added to well used to assessnon-specific binding. About 50 μL of 4× final concentration coldnociceptin (2.5 pM to SK-N-DZ cell lines and 1 μM to AGN P33 clonal cellline #6) was added to the non-specific binding wells, and 50 μL of 4×final concentrations of ³H-nociceptin (0 nM, 0.05 nM, 0.1 nM, 0.2 nM,0.4 nM, 0.8 nM, 1.6 nM, 3.1 nM, 6.3 nM, 12.5 nM, 25 nM, and 50 nM to theSK-N-DZ cell lines and 0, 0.01 nM, 0.02 nM, 0.039 nM, 0.078 nM, 0.156nM, 0.313 nM, 0.625 nM, 1.25 nM, 2.5 nM, 5.0 nM, and 10 nM to the AGNP33 clonal cell line #6) was added to both the total binding wells andthe non-specific binding wells to a final volume of 200 μL. Afterincubation at 37° C. for 30 minutes, the wells were washed twice in 0.5mL of cold Washing Buffer. Cells were then denatured in 200 μL 2 N NaOHand transferred to 20 mL scintillation vials containing 5 mL ofscintillation fluid. Raw data were used to plot the dose-response graphsand calculate the K_(d) for each sample. The raw data obtained weretransferred to SigmaPlot v10.0 and One Site Saturation fit was used todefine the dose-response curves under the equation category of LigandBinding. Graphical reports were generated and contained the followingparameters: R² (correlation coefficient), Bmax, and K_(d)±SE(Coefficient±standard error). Graphs of total binding, specific binding,and non-specific binding were obtained on the assay performed on theSK-N-DZ clonal cell lines #3, #15, and #22, and AGN P33 clonal cell line#6 cells. SK-N-DZ clonal cell lines #3 and #22 produced aconcentration-dependent and saturable binding of ³H-nociceptin. Underthe same experimental conditions, SK-N-DZ clonal cell line #15 produceda dose-dependent response of ³H-nociceptin, but not saturated at thehighest dose of 50 nM. Compared to the SK-N-DZ cell lines expressingendogenous ORL-1, cells from the AGN P33 clonal cell line #6 hadsignificantly higher affinity binding to ³H-nociceptin (highest dose was10 nM versus 50 nM in SK-N-DZ) with low non-specificity binding.

The saturation binding curves of SK-N-DZ clonal cell lines #3, #22, #15and AGN P33 clonal cell line #6 were used to estimate K_(d) and Bmaxvalues from three independent binding experiments per cell lineperformed in three different days. The rank order of these four celllines is: AGN P33 clonal cell line #6 (K_(d)=1.86 nM and Bmax=2.9fmol/cell)>SK-N-DZ clonal cell line #3 (K_(d)=14 nM and Bmax=0.6fmol/cell) SK-N-DZ clonal cell line #22 (K_(d)=17 nM and Bmax=0.6fmol/cell)>>SK-N-DZ clonal cell line #15 (K_(d)>50 nM). To get asaturated dose-response for SK-N-DZ clonal cell line #15, a higher doserange of ³H-nociceptin needs to be used. Table 16 summarizes the dataregarding the characterization of the specific plasma membranenociceptin-binding sites in three SK-N-DZ clonal cell lines, #3, #15,and #22, and AGN P33 clonal cell line #6 stable cell lines. The datashowed the following: 1) a high affinity site with very low non-specificbinding (K_(d), 1.8 nM, and Bmax 2.9 fmol per cell) in the AGN P33clonal cell line #6; 2) nociceptin-binding can be performed on SK-N-DZnative cells expressing endogenous receptor; 3) AGN P33 clonal cell line#6 had about 10-fold higher affinity to nociceptin than the SK-N-DZ celllines; 4) as seen in the cell-based potency assay, SK-N-DZ clonal celllines #3 and #22 (K_(d) 14-17 nM, Bmax 0.6 fmol per cell) had morereceptor sites per cell than SK-N-DZ clonal cell line #15 (not saturableunder the same dose range).

TABLE 18 Summary of ³H-nociceptin saturation binding assay for fourleading cell lines (n = 3 independent experiments) Cell Lines K_(d) (nM± SD) Bmax (fmol/cell) SK-N-DZ #3   14 ± 1.6 0.59 SK-N-DZ #15 >50 NDSK-N-DZ #22 16.7 ± 1.1 0.58 AGN P33 clonal cell 1.86 ± 0.1 2.89 line #6

To evaluate the sensitivity of re-targeted endopeptidase uptake, theamount of re-targeted endopeptidase receptor expressed at the mRNA levelwas assessed using RT-PCR. The amount of receptor expressed in the cellsis an important aspect of the characterization of the cell line beingused for testing and it is related to the sensitivity to re-targetedendopeptidases. The amount of expressed re-targeted endopeptidasereceptor can also be a tool for screening other potential cell lines andto eliminate cell lines that do not express the target receptor. Onemethod of measuring receptor expression is to quantify the amount ofre-targeted endopeptidase receptor mRNA using real time PCR (RT-PCR).

For opioid re-targeted endopeptidase, RNA was isolated from cells of anon-transfected parental SiMa cell line, cells from the AGN P33 clonalcell line #6, cells from the parental SK-N-DZ cell line, and cells fromthe SK-N-DZ clonal cell lines #3 and #22 grown in either serum freemedia or media with serum. The mRNA was converted to cDNA and the ORL-1was amplified and measured real time to determine the relative amountpresent in each cell line using the following oligonucleotide primersfor ORL-1: forward 5′-CACTCGGCTGGTGCTGGTGG-3′ (SEQ ID NO:148) andreverse 5′-AATGGCCACGGCAGTCTCGC-3′ (SEQ ID NO:149). The DNA isquantified by using SYBR® green which fluoresces relative to the amountof double stranded DNA (PCR product) present in the reaction. Plottingthe amount of fluorescence vs. number of cycles gives a logistic curvefor each reaction. The faster a reaction reaches the linear phase of thecurve the more ORL-1 receptor cDNA there is in the reaction. A controlRT reaction where no enzyme is added was be used to determine if thereis contamination. Since there is no RT enzyme present in this reaction,no cDNA will be produced. A PCR product cannot be produced using a RNAtemplate, so if a PCR curve appears in the −RT reaction, the onlypossibility is genomic DNA contamination. In the −RT reactions, no PCRplots appears, confirming there was minimal genomic DNA contamination(data not shown). Table 18 lists the cell lines with their CT value. TheCT is the number of PCR cycles it took for that corresponding PCRreaction to produce a signal above a set threshold. The amount of ORL-1receptor mRNA in a cell line can be compared to another by looking attheir corresponding CT values. According to the CT values, cells fromthe AGN P33 clonal cell line #6 had much more ORL-1 mRNA than cells fromthe parental SiMa cell line in serum free media (Ave CT: 28.6 vs. 17.3)and in media with serum (Ave CT: 26.1 vs. 16.5). Also, there appears tobe minimal difference in mRNA obtained from cells at passage 6 vs.passage 16 in the AGN P33 clonal cell line #6. Also, there are minimaldifferences in CT values and plots in the parental SK-N-DZ cell line vs.clonal cell line #3 and #22. This conclusion is true in cells grown inmedia with serum and serum free media and reflects the similarity ofthese cell lines observed in the cell-based potency assay for Noc/A.

TABLE 19 Average CT Values for ORL-1 Expression in Cell Lines Media Cellline CT average Serum Free Media SiMa Parental p26 28.6 SiMa hORL-1clone #6 p6 17.3 SiMa hORL-1 clone #6 p16 17.3 Complete Media SiMaParental p26 26.1 SiMa hORL-1 clone #6 p6 16.4 SiMa hORL-1 clone #6 p1616.6 Serum Free Media SK-N-DZ 26.3 SK-N-DZ clone #3 25.9 SK-N-DZ clone#22 26.6 Complete Media SK-N-DZ 26.2 SK-N-DZ clone #3 25.8 SK-N-DZ clone#22 26.4

Example 7 Development of α-SNAP-25 Monoclonal Antibodies thatSelectively Bind a SNAP-25 Epitope Having a Free Carboxyl-terminus atthe P₁ Residue of the BoNT/A Cleavage Site Scissile Bond

The following example illustrates how to make α-SNAP-25 monoclonalantibodies that can selectively bind to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond.

1. Generation of α-SNAP-25 Monoclonal Antibodies.

To develop monoclonal α-SNAP-25 antibodies that can selectively bind toa SNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond, the 13-residue peptide CDSNKTRIDEANQ_(COOH)(SEQ ID NO:38) was designed as a SNAP-25 cleavage product antigen. Thispeptide comprises a flexible linker region and a N-terminal Cysteineresidue for conjugation to KLH and amino acids 186-197 of human SNAP-25(SEQ ID NO:5) with a carboxylated C-terminal glutamine (SEQ ID NO:38).The generation of monoclonal antibodies to well-chosen, unique peptidesequences provides control over epitope specificity, allowing theidentification of a particular subpopulation of protein among a pool ofclosely related isoforms. Blast searches revealed that this peptide hashigh homology only to SNAP-25 and almost no possible cross-reactivitywith other proteins in neuronal cells. The sequence was also carefullyscrutinized by utilizing computer algorithms to determine hydropathyindex, protein surface probability, regions of flexibility, andfavorable secondary structure, followed by proper orientation andpresentation of the chosen peptide sequence. The peptide was synthesizedand conjugated to Keyhole Limpet Hemocyanin (KLH) to increaseimmunogenicity. Six Balb/c mice were immunized with this peptide, andafter three immunizations in about eight weeks, the mice were bled fortesting. The blood was allowed to clot by incubating at 4° C. for 60minutes. The clotted blood was centrifuged at 10,000×g at 4° C. for 10minutes to pellet the cellular debris. The resulting serum sample wasdispensed into 50 μl aliquots and stored at −20° C. until needed.

A similar strategy based on other SNAP-25 antigens disclosed in thepresent specification is used to develop α-SNAP-25 monoclonal antibodiesthat can selectively bind to a SNAP-25 having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond. For example, theSNAP-25 antigen of SEQ ID NO:45 can be conjugated to KLH instead of theSNAP-25 antigen of SEQ ID NO:38. As another example, the amino acids186-197 of human SNAP-25 from the SNAP-25 antigen of SEQ ID NO:38 can bereplaced with SEQ ID NO:32, SEQ ID NO:33, SEQ ID NO:34, SEQ ID NO:35,SEQ ID NO:36, SEQ ID NO:39, SEQ ID NO:40, SEQ ID NO:41, SEQ ID NO:42,SEQ ID NO:43, or SEQ ID NO:44.

2. Screening for the Presence of α-SNAP-25 Monoclonal Antibodies.

To determine the presence of an α-SNAP-25 monoclonal antibody that canselectively bind to a SNAP-25 antigen having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond, comparative ELISAand cell-based cleavage assay were performed using the extracted mouseserum. For comparative ELISA, two fusion proteins were constructed:BirA-HisTag®-SNAP-25₁₃₄₋₁₉₇ of SEQ ID NO:48 and theBirA-HisTag®-SNAP-25₁₃₄₋₂₀₆ of SEQ ID NO:49. BirA-HisTag®-SNAP-25₁₃₄₋₁₉₇comprised a naturally-biotinylated 16 amino acid BirA peptide of SEQ IDNO:50 amino-terminally linked to a SNAP-25 peptide comprising aminoacids 134-197 of SEQ ID NO:5. BirA-HisTag®-SNAP-25₁₃₄₋₂₀₆ comprised anaturally-biotinylated 16 amino acid BirA peptide of SEQ ID NO:50amino-terminally linked to a SNAP-25 peptide comprising amino acids134-206 of SEQ ID NO:5. These two substrates were suspended in 1×PBS ata concentration of 10 μg/mL BirA-HisTag®-SNAP-25₁₃₄₋₁₉₇ and theBirA-HisTag®-SNAP-25₁₃₄₋₂₀₆. The BirA-HisTag®-SNAP-25₁₃₄₋₁₉₇ and theBirA-HisTag®-SNAP-25₁₃₄₋₂₀₆ were coated onto separate plates by addingapproximately 100 μl of the appropriate Substrate Solution andincubating the plates at room temperature for one hour. Washed plateswere incubated at 37° C. for one hour in 0.5% BSA in 1×TBS containing a1:10 to 1:100 dilution of an antibody-containing serum derived from oneof the six immunized mice (Mouse 1, Mouse 2, Mouse 3, Mouse 4, Mouse 5,and Mouse 6). Primary antibody probed plates were washed four times for5 minutes each time in 200 μl TBS, 0.1% TWEEN-20® (polyoxyethylene (20)sorbitan monolaureate). Washed plates were incubated at 37° C. for 1hour in 1×TBS containing a 1:10,000 dilution of goat polyclonalanti-mouse IgG antibody conjugated to Horseradish peroxidase (PierceBiotechnology, Rockford, Ill.) as a secondary antibody. Secondaryantibody-probed plates were washed four times in 200 μl TBS, 0.1%TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate). Chromogenicdetection of the labeled SNAP-25 products were visualized by chromogenicdetection using ImmunoPure TMB substrate kit (Pierce Biotechnology,Rockford, Ill.). The development of a yellow color in theBirA-HisTag®-SNAP-25₁₃₄₋₁₉₇ coated plates, but not theBirA-HisTag®-SNAP-25₁₃₄₋₂₀₆ coated plates, indicated that the α-SNAP-25antibody preferentially recognized the SNAP-25₁₉₇ cleavage product. Theresulted indicated that of the six mice used for immunization, threemice (Mouse 2, Mouse 3, and Mouse 4) had higher titers and morespecificity towards a SNAP-25 antigen having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond.

These results were confirmed using an ELISA light chain activity assay.A 96-well Reacti-Bind Streptavidin coated plates (Pierce Biotechnology,Rockford, Ill.) were prepared by adding approximately 100 μl of thefollowing Substrate Solution: Rows A-C were coated with 100 μL ofBirA-HisTag®-SNAP-25₁₃₄₋₁₉₇ at twelve different concentrations; Rows D-Hwere coated with 100 μL of BirA-HisTag®-SNAP-25₁₃₄₋₂₉₆ at 10 μg/mL. Theplates were washed by aspirating the Substrate Solution and rinsing eachwell three times with 200 μl TBS, 0.1% TWEEN-20® (polyoxyethylene (20)sorbitan monolaureate). Dilutions of BoNT/A were pre-reduced at 37° C.for 20 minutes in BoNT/A Incubation Buffer (50 mM HEPES, pH 7.4, 1%fetal bovine serum, 10 μM ZnCl₂, 10 mM dithiothrietol) and 100 μl of thepre-reduced BoNT/A was added to the substrate-coated plates andincubated at 37° C. for 90 minutes. BoNT/A treated plates were washed byaspirating the BoNT/A Incubation Buffer and rinsing each plate threetimes with 200 μl TBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitanmonolaureate). Washed plates were incubated at 37° C. for one hour in0.5% BSA in 1×TBS containing a 1:10 to 1:100 dilution of theantibody-containing serum being tested. Primary antibody probed plateswere washed four times for 5 minutes each time in 200 μl TBS, 0.1%TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate). Washed plateswere incubated at 37° C. for 1 hour in 1×TBS containing a 1:10,000dilution of goat polyclonal anti-mouse IgG antibody conjugated toHorseradish peroxidase (Pierce Biotechnology, Rockford, Ill.) as asecondary antibody. Secondary antibody-probed plates were washed fourtimes in 200 μl TBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitanmonolaureate). Chromogenic detection of the labeled SNAP-25 productswere visualized by chromogenic detection using ImmunoPure TMB substratekit (Pierce Biotechnology, Rockford, Ill.). The development of a yellowcolor, which correlated with the presence of the SNAP-25₁₉₇ cleavageproduct was detected in BoNT/A treated samples, but not untreatedcontrols, using antibody-containing serum derived from all six immunizedmice (Mouse 1, Mouse 2, Mouse 3, Mouse 4, Mouse 5, and Mouse 6). Thus,the comparative ELISA analysis indicated that of the mice used forimmunization, three mice (Mouse 2, Mouse 3, and Mouse 4) had highertiters and more specificity towards a SNAP-25 antigen having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond.

For cell-based cleavage assay, a suitable density of PC12 cells wereplated into 60 mm² tissue culture plates containing 3 mL of anappropriate serum medium (Table 1). The cells were grown in a 37° C.incubator under 5% carbon dioxide until cells reached the appropriatedensity. A 500 μL transfection solution was prepared by adding 250 μL ofOPTI-MEM Reduced Serum Medium containing 15 μL of LipofectAmine 2000(Invitrogen Inc., Carlsbad, Calif.) incubated at room temperature for 5minutes to 250 μL of OPTI-MEM Reduced Serum Medium containing 10 μg of apQBI-25/GFP-BoNT/A-LC expression construct (SEQ ID NO:51). ThepQBI-25/GFP-BoNT/A-LC expression construct comprises a pQBI-25expression vector (Qbiogene Inc., Carlsbad, Calif.) whose promoterelements are functionally linked to a polynucleotide encoding theGFP-BoNT/A light chain of SEQ ID NO:52. This transfection mixture wasincubated at room temperature for approximately 20 minutes. The mediawas replaced with fresh unsupplemented media and the 500 μL transfectionsolution was added to the cells. The cells were then incubated in a 37°C. incubator under 5% carbon dioxide for approximately 6 to 18 hours.The cells were washed and harvested as described in Example II. Todetect for the presence of the cleaved SNAP-25₁₉₇ product, an aliquotfrom each harvested sample was analyzed by Western blot as described inExample II, except that the primary antibody used was a 1:1,000 dilutionof the antibody-containing serum and the secondary antibody used was a1:20,000 of mouse α-IgG Horseradish Peroxidase (Pierce Biotechnology,Rockford, Ill.). A single band corresponding to the SNAP-25₁₉₇ cleavageproduct was detected in BoNT/A treated samples, but not untreatedcontrols, using antibody-containing serum derived from three mice (Mouse2, Mouse 3, and Mouse 4). Thus, the cell-based cleavage assay indicatedthat of the mice used for immunization, three mice (Mouse 2, Mouse 3,and Mouse 4) had higher titers and more specificity towards a SNAP-25antigen having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond.

3. Production of Hybridomas.

To make hybridomas producing α-SNAP-25 monoclonal antibodies that canselectively bind to a SNAP-25 antigen having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond, the spleen fromMouse 2 was harvested three days subsequent to a final “booster”immunization and the spleen cells were fused with myeloma cells P3-X63Ag8.653 using standard hybridoma protocols. These cells were plated intofive 96-well plates and hybrids were selected using HAT medium. Within8-14 days after fusion, the first screening of the approximately 480parent clones was carried out using comparative ELISA with theBirA-HisTag®-SNAP-25₁₃₄₋₁₉₇ and the BirA-HisTag®-SNAP-25₁₃₄₋₂₀₆ peptidescoated in two separate plates. The comparative ELISA provided a quickscreen method to identify hybridomas producing antibodies specific forthe cleaved SNAP-25₁₉₇. The top 18 clones were subjected to furtherscreening using the cell-based cleavage assay described above andimmunostaining of LC/A transfected cells. (Table 20).

TABLE 20 Analysis of Supernatants Containing α-SNAP-25 MonoclonalAntibody Comparative ELISA OD OD Cell-Based Assay SNAP- SNAP- SNAP-SNAP- Clone 25₁₉₇ 25₂₀₆ Ratio_(197/206) Ratio_(206/197) 25₁₉₇ 25₂₀₆ 1D31.805 0.225 8.02 0.13 +++ − 1F12 0.365 0.093 3.92 0.25 − − 1G10 0.5900.137 4.31 0.23 ++ − 1H1 0.335 0.121 2.77 0.36 − − 1H8 0.310 0.302 1.030.97 + − 2C9 0.139 0.274 0.51 1.97 − − 2E2 0.892 0.036 24.78 0.04 ++ −2E4 0.228 0.069 3.30 0.30 + − 2F11 1.095 1.781 0.61 1.63 − − 3C1 1.2680.053 23.92 0.04 ++ − 3C3 0.809 0.052 15.56 0.06 ++ − 3E1 0.086 0.1550.55 1.80 0 − 3E8 2.048 0.053 38.64 0.03 +++ − 3G2 0.053 0.158 0.34 2.98− − 4D1 0.106 0.218 0.49 2.06 − − 4G6 0.061 0.159 0.38 2.61 − − 5A50.251 0.106 2.37 0.42 + − 5F11 0.243 0.061 3.98 0.25 − −

Clones 1D3, 1G10, 2E2, 3C1, 3C3, and 3E8 were further cloned by limitingdilution because the conditioned media produced by these clonescomprised α-SNAP-25 antibodies with a preferential binding specificityhaving a ratio_(197/206) of at least 4:1 for the SNAP-25₁₉₇ cleavageproduct relative to the SNAP-25₂₀₆ uncleaved substrate and detected theSNAP-25₁₉₇-cleavage product using the cell-based cleavage assay and theimmunostaining of PC12 cells transfected with GFP-LC/A. Similarly clones2C9, 2F11, 3G2, 4D1 and 4G6 were further cloned by limiting dilutionbecause the conditioned media produced by these clones comprisedα-SNAP-25 antibodies with a preferential binding specificity having aratio_(206/197) of at least 1.5:1 for the SNAP-25₂₀₆ uncleaved substraterelative to the SNAP-25₁₉₇ cleavage product and detected theSNAP-25₂₀₆-uncleaved substrate using the cell-based cleavage assay.These single-cell derived clones were screened again using comparativeELISA, cell-based cleavage, and immunostaining to confirm their affinityand specificity, and the antibodies were isotyped using standardprocedures. Ascites were produced from clones 1 D3B8 (IgM.k), 1G10A12(IgG3.k), 2C9B10 (IgG3.k), 2E2A6 (IgG3.k), 2F11B6 (IgM.k), 3C1A5(IgG2a.k), and 3C3E2 (IgG2a.k). Clone 3E8 stopped producing antibodiesduring the cloning process and could not be further evaluated.

4. Evaluation of Binding Specificity of α-SNAP-25 Monoclonal Antibodies.

To evaluate binding specificity of an α-SNAP-25 monoclonal antibody thatcan selectively bind to a SNAP-25 antigen having a carboxyl-terminus atthe P₁ residue of the BoNT/A cleavage site scissile bond, ascites fromclones 1D3B8, 1G10A12, 2C9B10, 2E2A6, 2F11B6, 3C1A5, and 3C3E2 were usedto detect SNAP-25 cleavage product using the cell-based activity assay,immunocytochemistry and immunoprecipitation.

For the cell-based activity assay, binding specificity was determined byanalyzing the ability of α-SNAP-25 antibody-containing ascites to detectthe uncleaved SNAP-25₂₀₆ substrate and the cleaved SNAP-25₁₉₇ product byWestern blot analysis. A suitable density of PC12 cells were plated into60 mm² tissue culture plates containing 3 mL of an appropriate serummedium, grown in a 37° C. incubator under 5% carbon dioxide until anappropriate cell density was reached, and transfected with the either atransfection solution lacking the pQBI-25/GFP-BoNT/A-LC expressionconstruct (untransfected cells) or a transfection solution containingthe pQBI-25/GFP-BoNT/A-LC expression construct (transfected cells) asdescribed above. The cells were washed and harvested as described inExample I. To detect for the presence of both the uncleaved SNAP-25₂₀₆substrate and the cleaved SNAP-25₁₉₇ product, an aliquot from eachharvested sample was analyzed by Western blot as described in Example I,except that the primary antibody used was a 1:100 dilution of theα-SNAP-25 monoclonal antibody-containing ascites and the secondaryantibody used was a 1:20,000 of α-mouse IgG conjugated to HorseradishPeroxidase (Pierce Biotechnology, Rockford, Ill.). In addition, threecommercially available mouse α-SNAP-25 monoclonal antibodies weretested. SMI-81 (Sternberger Monoclonals Inc., Lutherville, Md.), anα-SNAP-25 antibody the manufacturer indicates detects both the uncleavedSNAP-25₂₀₆ substrate and the cleaved SNAP-25₁₉₇ product, was used at a15,000 dilution according to the manufacturer's recommendations. MC-6050(Research & Diagnostic Antibodies, Las Vegas, Nev.), an α-SNAP-25antibody the manufacturer indicates detects both the uncleavedSNAP-25₂₀₆ substrate and the cleaved SNAP-25₁₉₇ product, was used at a1:100 dilution according to the manufacturer's recommendations. MC-6053(Research & Diagnostic Antibodies, Las Vegas, Nev.), an α-SNAP-25antibody the manufacturer indicates detects only the cleaved SNAP-25₁₉₇product, was used at a 1:100 dilution according to the manufacturer'srecommendations.

Table 21 indicates the α-SNAP-25 antibody-containing ascites thatdetected only the SNAP-25₁₉₇ cleavage product. The cell-based cleavageassay indicated that ascites produced from clones 1D3B8, 2C9B10, 2E2A6,3C1A5, and 3C3E2 synthesize an α-SNAP-25 monoclonal antibody having highbinding specificity for the SNAP-25₁₉₇ cleavage product that allows forthe selective recognition of this cleavage product relative to theSNAP-25₂₀₆ uncleaved substrate. Commercial antibody SMI-81 detected theSNAP-25₂₀₆ uncleaved substrate, but only poorly recognized theSNAP-25₁₉₇ cleavage product (Table 21). Surprisingly, commercialantibody MC-6050 only detected the SNAP-25₂₀₆ uncleaved substrate, andfailed to recognize the SNAP-25₁₉₇ cleavage product (Table 21). Evenmore surprisingly, commercial antibody MC-6050 only detected theSNAP-25₂₀₆ uncleaved substrate, and failed to recognize the SNAP-25₁₉₇cleavage product, even though the manufacturer advertises that thisantibody selectively detects the SNAP-25₁₉₇ cleavage product (Table 21).Thus, this analysis indicates that while 1D3B8, 2C9B10, 2E2A6, 3C1A5,and 3C3E2 exhibit suitable selectivity for the SNAP-25₁₉₇ cleavageproduct, 1G10A12 and 2F11B6 do not. In addition, commercial antibodiesSMI-81, MC-6050 and MC-6053 all are unsuitable for the immuno-basedmethods disclosed in the present application because all failed toselectivity detect the SNAP-25₁₉₇ cleavage product.

For immunocytochemistry analysis, binding specificity was determined byanalyzing the ability of α-SNAP-25 antibody-containing ascites to detectthe uncleaved SNAP-25₂₀₆ substrate and the cleaved SNAP-25₁₉₇ product byimmunostaining. See e.g., Ester Fernandez-Salas et al., Plasma MembraneLocalization Signals in the Light Chain of Botulinum Neurotoxin, Proc.Natl. Acad. Sci., U.S.A. 101(9): 3208-3213 (2004). A suitable density ofPC12 cells were plated, grown, and transfected with either atransfection solution lacking the pQBI-25/GFP-BoNT/A-LC expressionconstruct (untransfected cells) or a transfection solution containingthe pQBI-25/GFP-BoNT/A-LC expression construct (transfected cells) asdescribed above. The cells were washed in 1×PBS and fixed in 5 mL of PAFat room temperature for 30 minutes. Fixed cells were washed in phosphatebuffered saline, incubated in 5 mL of 0.5% Triton® X-100 (polyethyleneglycol octylphenol ether) in 1×PBS, washed in 1×PBS, and permeabilizedin 5 mL of methanol at −20° C. for six minutes. Permeabilized cells wereblocked in 5 mL of 100 mM glycine at room temperature for 30 minutes,washed in 1×PBS, and blocked in 5 mL of 0.5% BSA in 1×PBS at roomtemperature for 30 minutes. Blocked cells were washed in 1×PBS andincubated at room temperature for two hours in 0.5% BSA in 1×PBScontaining a 1:10 dilution of an ascites from a clonal hybridoma cellline being tested. Primary antibody probed cells were washed three timesfor 5 minutes each time in 1×PBS. Washed cells were incubated at roomtemperature for 2 hours in 1×PBS containing a 1:200 dilution of goatpolyclonal anti-mouse immunoglobulin G, heavy and light chains (IgG,H+L) antibody conjugated to ALEXA® FLUOR 568 (Invitrogen Inc., Carlsbad,Calif.) as a secondary antibody. Secondary antibody-probed cells werewashed three times for 5 minutes each time in 1×PBS. Washed cells wereprepared for microscopic examination by mounting in VECTASHIELD®Mounting Media (Vector Laboratories, Burlingame, Calif.) andcoverslipped. Images of signal detection were obtained with a Leicaconfocal microscope using appropriate laser settings. Table 21 indicatesthat the α-SNAP-25 antibody-containing ascites that specificallydetected the SNAP-25₁₉₇-cleavage product. The immunocytochemistryanalysis indicated that ascites produced from clones 1D3B8, 2C9B10,2E2A6, 3C1A5, and 3C3E2 synthesize an α-SNAP-25 monoclonal antibodyhaving high binding specificity for the SNAP-25₁₉₇ cleavage product thatallows for the preferential recognition of this cleavage productrelative to the SNAP-25₂₀₆ uncleaved substrate.

For immunoprecipitation analysis, binding specificity was determined byanalyzing the ability of Protein A (HiTrap™ Protein A HP Columns, GEHealthcare, Amersham, Piscataway, N.J.), purified α-SNAP-25 monoclonalantibodies to precipitate the uncleaved SNAP-25₂₀₆ substrate and thecleaved SNAP-25₁₉₇ product. See e.g., Chapter 8 Storing and PurifyingAntibodies, pp. 309-311, Harlow & Lane, supra, 1998a. A suitable densityof PC12 cells were plated, grown, and transfected with either atransfection solution containing a pQBI-25/GFP expression construct(control cells; SEQ ID NO:53) or a transfection solution containing thepQBI-25/GFP-BoNT/A-LC expression construct (experimental cells) asdescribed above. The pQBI-25/GFP expression construct comprises anexpression vector whose promoter elements are functionally linked to apolynucleotide encoding GFP of SEQ ID NO:54. After an overnightincubation, the cells were washed by aspirating the growth media andrinsing each well with 200 μL 1×PBS. To harvest the cells, the PBS wasaspirated, the cells were lysed by adding an Immunoprecipitation LysisBuffer comprising 50 mM HEPES, 150 mM NaCl, 1.5 mM MgCl₂, 1 mM EGDT, 10%glycerol, 1% Triton® X-100 (polyethylene glycol octylphenol ether) and a1× COMPLETE™ Protease inhibitor cocktail (Roche Applied Biosciences,Indianapolis, Ind.) and incubating at 4° C. for one hour. The lysedcells were centrifuged at 3,000×g at 4° C. for 10 minutes to removecellular debris and the supernatant transferred to a clean tube anddiluted to a protein concentration of approximately 1 mg/mL.Approximately 5 μg of purified monoclonal antibody was added to 0.5 mLof diluted supernatant and incubated at 4° C. for two hours. Afterprimary antibody incubation, approximately 50 μL of immobilized ProteinG (Pierce Biotechnology, Rockford, Ill.) was added to the dilutedsupernatant and incubated at 4° C. for one hour. The incubatedsupernatant was washed three times for 30 minutes each time by adding0.5 mL of Immunoprecipitation Lysis Buffer, centrifuging at 300×g at 4°C. for one minute to pellet the immobilized Protein G, and decanting thesupernatant. After washing, the pellet was resuspended in 30 μl of 1×SDSLoading Buffer and the sample was heated to 95° C. for 5 minutes. Todetect for the presence of both the uncleaved SNAP-25₂₀₆ substrate andthe cleaved SNAP-25₁₉₇ product, an aliquot from each harvested samplewas analyzed by Western blot as described in Example I, except that theprimary antibody used was a 1:1,000 dilution of the α-SNAP-25 polyclonalantibody serum (see Example V) and the secondary antibody used was a1:20,000 of rabbit α-IgG Horseradish Peroxidase (Pierce Biotechnology,Rockford, Ill.). Table 21 indicates the α-SNAP-25 antibody-containingascites that specifically pulled down the SNAP-25₁₉₇-cleavage product byimmunoprecipitation analysis. The immunoprecipitation analysis indicatedthat ascites produced from clones 2E2A6 and 3C1A5 synthesize anα-SNAP-25 monoclonal antibody having high binding specificity for theSNAP-25₁₉₇ cleavage product that allows for the preferential recognitionof this cleavage product relative to the SNAP-25₂₀₆ uncleaved substrate.

TABLE 21 Analysis of Clone Ascites Containing α-SNAP-25 MonoclonalAntibody Cell-Based Assay Immunocytochemistry Immunoprecipitation CloneSNAP-25₁₉₇ SNAP-25₂₀₆ SNAP-25₁₉₇ SNAP-25₂₀₆ SNAP-25₁₉₇ SNAP-25₂₀₆ 1D3B8++ − ++ − Not Tested Not Tested 1G10A12 ++ ++ Not Tested Not Tested NotTested Not Tested 2C9B10 ++ − ++ − Not Tested Not Tested 2E2A6 ++ − ++ −++ − 2F11B6 + + + + Not Tested Not Tested 3C1A5 ++ − ++ − ++ − 3C3E2 + −Not Tested Not Tested Not Tested Not Tested MC-6050 − + Not Tested NotTested Not Tested Not Tested MC-6053 − + Not Tested Not Tested NotTested Not Tested SMI-81 −/+ ++ Not Tested Not Tested Not Tested NotTested

5. Evaluation of Binding Affinity of α-SNAP-25 Monoclonal Antibodies

To determine the binding affinity of an α-SNAP-25 monoclonal antibodyshowing high binding specificity for either the SNAP-25₁₉₇ cleavageproduct or the SNAP-25₂₀₆ uncleaved substrate, binding affinity assayswere performed on a BIAcore® 3000 instrument using carboxymethyl dextran(CM5) sensor chips (BIAcore, Inc., Piscataway, N.J.). Runs wereconducted at 25° C. with HBS-EP buffer comprising 10 mM HEPES (pH 7.4),150 mM sodium chloride, 3 mM EDTA, 0.005% (v/v) surfactant P20 at a flowrate of 10 μL/min. SNAP-25 peptides comprising amino acids 134-197 ofSEQ ID NO:5 (SNAP-25₁₃₄₋₁₉₇) or amino acids 134-206 of SEQ ID NO:5(SNAP-25₁₃₄₋₂₀₆) were covalently attached to the surface of the CM5sensor chips using standard amine coupling. Briefly, the CM5 chips wereactivated by a 7 minute injection of a mixture of 0.2 M1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and 0.05 MN-hydroxysuccimide; the SNAP-25 peptides were then injected in 10 mMsodium acetate (pH 4.0) for 20 min at a flow rate of 10 μL/min; andunreacted succimide esters were blocked by a 7-min injection of 1 Methanolamine hydrochloride, pH 8.5. The immobilized amount ofSNAP-25₁₃₄₋₁₉₇ or SNAP-25₁₃₄₋₂₀₆ on the chip was reflected by a 100-150increase in response units (about 0.10-0.15 ng/mm²). Antibody samplescomprising either ascites or purified monoclonal antibodies producedfrom clones 1D3B8, 2C9B10, 2E2A6, 3C1A5, and 3C3E2, as well as,commercially available α-SNAP-25 antibodies were passed over the surfaceof the CM5 chips allowing an association time of 10 min and adissociation time of 20 min. The surfaces were regenerated between runsby a 1 minute injection of 10 mM glycine-HCl (pH 2.5) at a flow rate of15 μL/min. Sensorgram curves were fitted to a 1:1 kinetic binding modelwith the BIAevaluation 3.0 software.

The results indicate that both 2E2A6 and 3C1A5 were highly specific forcleaved SNAP-25₁₉₇ product over SNAP-25 uncleaved substrate (Table 22).When compared to the binding affinities of MC-6050 and MC-6053, 1D3B6had an approximately 10-fold higher equilibrium disassociation constantfor the SNAP-25 cleavage product relative to these commercial antibodies(Table 22). Interestingly, 2E2A6 had only a slightly lower equilibriumdisassociation constant for the SNAP-25 cleavage product relative tothese commercial antibodies (0.405 nM versus 0.497 and 0.508)(Table 22).As neither of these commercial α-SNAP-25 antibodies selectivelyrecognized the SNAP-25 cleavage product (Table 21), an equilibriumdisassociation constant lower than about 0.5 nM appears, in part,critical to achieve such selectivity. Similarly, when compared to thebinding affinities of MC-6050 and MC-6053, 2E2A6 had an about at leastone-fold slower off rate/dissociation constant (6.74×10⁻⁵ versus8.82×10⁻⁴ s⁻¹ and 1.18×10⁻³ s⁻¹) (Table 22). This further suggests thatan off rate/dissociation constant lower than about 8.82×10⁻⁴ appears, inpart, critical to achieve selective binding for the SNAP-25 cleavageproduct. This result is consistent with 1 D3B8, which had an offrate/dissociation constant of 5.78×10⁻⁵ s⁻¹ (Table 22).

TABLE 22 Analysis of Binding Affinity α-SNAP-25 Monoclonal AntibodiesSPR 1D3B8 2E2A6 Parameter SNAP-25₁₉₇ SNAP-25₂₀₆ ^(a) SNAP-25₁₉₇SNAP-25₂₀₆ ^(b) Ka (M⁻¹ s⁻¹) 1.06 × 10⁶   — 1.70 × 10⁶   — (1.66 ×10⁵)   (—) Kd (s⁻¹) 5.78 × 10⁻⁵ — 1.53 × 10⁻⁴ — (6.74 × 10⁻⁵) (—) KD(nM) 0.050 — 0.090 — (0.405) (—) SPR 3C1A5 2C9B10 Parameter SNAP-25₁₉₇SNAP-25₂₀₆ ^(c) SNAP-25₁₉₇ SNAP-25₂₀₆ ^(d) Ka (M⁻¹ s⁻¹) 2.17 × 10⁵   —1.15 × 10⁴   — Kd (s⁻¹) 2.88 × 10⁻⁴ — 3.11 × 10⁻⁴ — KD (nM) 1.33 —27.1   — SPR MC-6050 MC-6053 Parameter SNAP-25₁₉₇ SNAP-25₂₀₆ SNAP-25₁₉₇SNAP-25₂₀₆ Ka (M⁻¹ s⁻¹) 1.78 × 10⁶   3.06 × 10²   2.32 × 10⁶   1.06 ×10²   Kd (s⁻¹) 8.82 × 10⁻⁴ 6.07 × 10⁻³ 1.18 × 10⁻³ 2.56 × 10⁻⁵ KD (nM)0.497 19,800 0.508 240 ^(a)No binding was observed when up to 125 nM ofα-SNAP-25 monoclonal antibody 1D3B8 was passed over the surface of theCM5 sensor chip after a 10 minute association time. ^(b)No binding wasobserved when up to 10 μM of α-SNAP-25 monoclonal antibody 2E2A6 waspassed over the surface of the CM5 sensor chip after a 10 minuteassociation time. ^(c)No binding was observed when up to 100 nM ofα-SNAP-25 monoclonal antibody 3C1A5 was passed over the surface of theCM5 sensor chip after a 10 minute association time. ^(d)No binding wasobserved when up to 100 nM of α-SNAP-25 monoclonal antibody 2C9B10 waspassed over the surface of the CM5 sensor chip after a 10 minuteassociation time.

To compare the six different antibodies, the on-rate (ka) and off-rate(kd) for each was normalized using a program from the BIA evaluation 4.1software. For comparison of the on-rates, the data were firstindividually trimmed by deleting the re-generation portion and theinjection spikes, and then normalized to a 0 to 100 scale. Forcomparison of the off-rate, the data were normalized to the injectionstop/top point. This analysis showed that 2C9B10 had a much sloweron-rate than the other antibodies (FIG. 7A), and that MC-6053 has a muchfaster off-rate (dissociation) that the other antibodies (FIG. 7B). Thefast off-rate of MC-6053 indicates that this antibody will not performwell in the methods disclosed in the present specification because thisantibody will have difficulty staying bound to the substrate antigenduring the washing steps.

6. Sequencing of the Epitope from Isolated α-SNAP-25 MonoclonalAntibodies.

To determine the epitope of an isolated α-SNAP-25 monoclonal antibodythat can selectively bind to a SNAP-25 antigen having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond, the polynucleotide molecule encoding the variable heavy (V_(H))and variable light (V_(L)) chains of the α-SNAP-25 monoclonal antibodyproduced by hybridomas 1D3B8, 2C9B10, 2E2A6, 3C1A5 and 3C3E2 weresequenced. mRNA was extracted and purified from each hybridoma usingstandard protocols and reversed transcribed into cDNA using either anoligo dT anti-sense primer or a gene-specific (murine IgG1 CH and kappaCL) anti-sense primer. Specific murine and human constant domain primerswere used to amplify the cDNA by PCR after cDNA production to determinethe isotype of the antibody. Degenerate V_(H) and V_(L) primers wereused to amplify the variable domains from the cDNA. For 5′RACE, ahomopolymeric dCTP tail was added to the 3′ end of the cDNA. The heavyand light chains were then amplified with an oligo dG sense primer and agene specific (CH/KC) anti-sense primer. PCR products included thesequence of the signal peptide, variable domains and constant domains upto the anti-sense primer. The PCR products were gel purified to removesmall fragments, and cloned into a blunt or TA vector for sequencing.Five independent clones for each chain were sequenced and alignments ofV_(H) and VL chains and consensus sequences were determined. Methodsused to determine the V_(H) and V_(L) amino acid sequences are describedin, e.g., Roger A. Sabbadini, et al., Novel Bioactive Lipid Derivativesand Methods of Making and Using Same, U.S. Patent Publication2007/0281320; and Peter Amersdorfer, et al., Molecular Characterizationof Murine Humoral Immune Response to Botulinum Neurotoxin Type A BindingDomain as Assessed by Using Phage Antibody Libraries, 65 (9) Infect.Immun. 3743-3752, each of which is hereby incorporated by reference inits entirety. In addition, commercial services are available to sequencethe variable heavy (V_(H)) and variable light (V_(L)) chains of anantibody and identify the CDR regions, see, e.g., Fusion AntibodiesLtd., Northern Ireland. In one case, for the 3C1A5 V_(L) region, theamino acid sequence was also determined by separating the affinitypurified antibody by high resolution 2DE electrophoresis and thensubjecting the protein to peptide fragmentation fingerprinting analysisusing high resolution nanoLC-MSMS after proteolytic digestion.

The polynucleotide sequence comprising the V_(H) and V_(L) chains of theα-SNAP-25 monoclonal antibody produced by the hybridomas disclosed inthe present specification is as follows: 1D3B8 V_(H) (SEQ ID NO:71),2C9B10 V_(H) (SEQ ID NO:73), 2E2A6 V_(H) (SEQ ID NO:75), 3C1A5 V_(H)(SEQ ID NO:77), 3C3E2 V_(H) variant 1 (SEQ ID NO:79), 3C3E2 V_(H)variant 2 (SEQ ID NO:81), 3C3E2 V_(H) variant 3 (SEQ ID NO:132), 1D3B8V_(L) (SEQ ID NO:83), 2C9B10 V_(L) (SEQ ID NO:85), 2E2A6 V_(L) (SEQ IDNO:87), 3C1A5 V_(L) (SEQ ID NO:89), and 3C3E2 V_(L) (SEQ ID NO:91). Theamino acid sequence comprising the V_(H) and V_(L) chains of theα-SNAP-25 monoclonal antibody produced by the hybridomas disclosed inthe present specification is as follows: 1D3B8 V_(H) (SEQ ID NO:72),2C9B10 V_(H) (SEQ ID NO:74), 2E2A6 V_(H) (SEQ ID NO:76), 3C1A5 V_(H)(SEQ ID NO:78), 3C3E2 V_(H) variant 1 (SEQ ID NO:80), 3C3E2 V_(H)variant 2 (SEQ ID NO:82); 3C3E2 V_(H) variant 2 (SEQ ID NO:133), 1 D3B8V_(L) (SEQ ID NO:84), 2C9B10 V_(L) (SEQ ID NO:86), 2E2A6 V_(L) (SEQ IDNO:88), 3C1A5 V_(L) (SEQ ID NO:90), and 3C3E2 V_(L) (SEQ ID NO:92). Theamino acid sequences comprising the V_(H) and V_(L) CDR domains of theα-SNAP-25 monoclonal antibody produced by the hybridomas 1D3B8, 2C9B10,2E2A6, 3C1A5, and 3C3E2 are given in Table 23.

TABLE 23 CDR Sequences of V_(H) and V_(L) domains from α-SNAP-25Monoclonal Antibodies CDR Sequence Identified In SEQ ID NO: V_(H) CDR 1TFTDHSIH 2E2A6 93 2C9B10 3C1A5 V_(H) CDR 1 TFTNYVIH 3C3E2 94 V_(H) CDR 1IFTDHALH 1D3B8 95 V_(H) CDR 2 YIFPGNGNIEYNDKFKG 2E2A6 96 V_(H) CDR 2YLFPGNGNFEYNEKFKG 2C9B10 97 3C1A5 V_(H) CDR 2 YINPYNDGSKYNEKFKG 3C3E2 98V_(H) CDR 2 YIFPGNGNIEYNEKFKG 1D3B8 99 V_(H) CDR 3 KRMGY 2E2A6 100 3C1A5V_(H) CDR 3 KKMDY 2C9B10 101 1D3B8 V_(H) CDR 3 ARMDY 3C3E2var1 102 V_(H)CDR 3 ARMGY 3C3E2var2 134 V_(H) CDR 3 ARHLANTYYYFDY 3C3E2var3 135 V_(L)CDR 1 RSSQSIVHSNGNTYLE 1D3B8 103 V_(L) CDR 1 RTTENIYSYFV 2C9B10 104V_(L) CDR 1 KSSQSLLYTNGKTYLT 2E2A6 105 V_(L) CDR 1 KSSQSLLNTNGKTYLT3C1A5 106 V_(L) CDR 1 RASQNIGNYLH 3C3E2 107 V_(L) CDR 2 KVSNRFS 1D3B8108 V_(L) CDR 2 NAKSLAE 2C9B10 109 V_(L) CDR 2 LVSELDS 2E2A6 110 V_(L)CDR 2 LVSKLDS 3C1A5 111 V_(L) CDR 2 YASQSIS 3C3E2 112 V_(L) CDR 3FQGSHVPPT 1D3B8 113 V_(L) CDR 3 QHHYGTPYT 2C9B10 114 V_(L) CDR 3LQSAHFPFT 2E2A6 115 V_(L) CDR 3 LQSSHFPFT 3C1A5 116 V_(L) CDR 3QQSDTWPLT 3C3E2 117

Non-limiting examples of amino acid sequences comprising V_(H) CDRdomain variants of the α-SNAP-25 monoclonal antibody produced by thehybridomas disclosed in the present specification include V_(H) CDR1variant SEQ ID NO:118 for 1D3B8; V_(H) CDR1 variant SEQ ID NO:119 for2C9B10, 2E2A6 and 3C1A5 V_(H); V_(H) CDR1 variant SEQ ID NO:120 for3C1A5 V_(H) and 3C3E2 variant 3; V_(H) CDR2 variant SEQ ID NO:121 for1D3B8 and 2E2A6; V_(H) CDR2 variant SEQ ID NO:122 for 2C9B10 and 3C1A5V_(H); V_(H) CDR2 variant SEQ ID NO:123 for 3C1A5 V_(H) and 3C3E2variant 3; V_(H) CDR3 variant MDY for 1 D3B8 and 2C9B10; V_(H) CDR3variant MGY for 2E2A6 and 3C1A5 V_(H); and V_(H) CDR3 variant SEQ IDNO:124 for 3C1A5 V_(H) and 3C3E2 variant 3. Non-limiting examples ofamino acid sequences comprising V_(L) CDR domain variants of theα-SNAP-25 monoclonal antibody produced by the hybridomas disclosed inthe present specification include V_(L) CDR1 variant SEQ ID NO:125 for1D3B8; V_(L) CDR1 variant SEQ ID NO:126 for 2C9B10; V_(L) CDR1 variantSEQ ID NO:127 for 2E2A6; V_(L) CDR1 variant SEQ ID NO:128 for 3C1A5;V_(L) CDR1 variant SEQ ID NO:129 for 3C3E2; V_(L) CDR2 variant KVS for 1D3B8; V_(L) CDR2 variant NAK for 2C9B10; V_(L) CDR2 variant LVS for2E2A6; V_(L) CDR2 variant YAT for 3C1A5; and V_(L) CDR2 variant YAS for3C3E2.

Example 8 Development of α-SNAP-25 Polyclonal Antibodies thatSelectively Bind a SNAP-25 Epitope Having a Free Carboxyl-Terminus atthe P₁ Residue of the BoNT/A Cleavage Site Scissile Bond

The following example illustrates how to make α-SNAP-25 polyclonalantibodies that can selectively bind to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond.

To develop α-SNAP-25 polyclonal antibodies that can selectively bind toa SNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond, the 10-residue peptide CGGGRIDEANQ (SEQ IDNO:46) was designed as a SNAP-25 cleavage product antigen. This peptidecomprising a N-terminal Cysteine residue for conjugation to KLH, aG-spacer flexible spacer (GGG) linked to amino acids 191-197 of humanSNAP-25 (SEQ ID NO:5) and has a carboxylated C-terminal glutamine. Blastsearches revealed that this peptide has high homology only to SNAP-25and almost no possible cross-reactivity with other proteins in neuronalcells. The sequence was also carefully scrutinized by utilizing computeralgorithms to determine hydropathy index, protein surface probability,regions of flexibility, and favorable secondary structure, followed byproper orientation and presentation of the chosen peptide sequence. Thepeptide was synthesized and conjugated to Keyhole Limpet Hemocyanin(KLH) to increase immunogenicity. Before the animals were immunized,naïve rabbits were first screened against cell lysates from candidatecell lines in a Western blot in order to identify animals that had noimmunoreactivity to the proteins present in the cell lysates. Twopre-screened rabbits were immunized with this peptide, and after threeimmunizations in about eight weeks, the rabbits were bled for testing.The blood was allowed to clot by incubating at 4° C. for 60 minutes. Theclotted blood was centrifuged at 10,000×g at 4° C. for 10 minutes topellet the cellular debris. The resulting serum sample was dispensedinto 50 μL aliquots and stored at −20° C. until needed.

A similar strategy based on other SNAP-25 antigens disclosed in thepresent specification is used to develop α-SNAP-25 polyclonal antibodiesthat can selectively bind to a SNAP-25 having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond. For example, theSNAP-25 antigen of SEQ ID NO:47 can be conjugated to KLH instead of theSNAP-25 antigen of SEQ ID NO:46. As another example, the amino acids191-197 of human SNAP-25 from the SNAP-25 antigen of SEQ ID NO:38 can bereplaced with SEQ ID NO:33, SEQ ID NO:34, SEQ ID NO:35, SEQ ID NO:36,SEQ ID NO:37, SEQ ID NO:39, SEQ ID NO:40, SEQ ID NO:41, SEQ ID NO:42,SEQ ID NO:43, or SEQ ID NO:44.

2. Screening for the Presence of α-SNAP-25 Polyclonal Antibodies.

To determine the presence of α-SNAP-25 polyclonal antibodies that canselectively bind to a SNAP-25 antigen having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond, comparative ELISAand cell-based cleavage assays were performed using the extracted rabbitserum as described in Example III. The serum from both rabbits containedα-SNAP-25 polyclonal antibodies that can selectively bind to a SNAP-25antigen having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond. The α-SNAP-25 rabbit polyclonal antibodieswere designated as NTP 22 and NTP 23.

3. Purification of α-SNAP-25 Polyclonal Antibodies.

To purify α-SNAP-25 polyclonal antibodies that can selectively bind to aSNAP-25 antigen having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond, NTP 22 and NTP 23 antibodies fromrabbit serum were purified using affinity columns containing the SNAP-25antigen of SEQ ID NO:46.

4. Evaluation of Binding Specificity of α-SNAP-25 Polyclonal Antibodies.

To evaluate binding specificity of an α-SNAP-25 polyclonal antibody thatcan selectively bind to a SNAP-25 antigen having a carboxyl-terminus atthe P₁ residue of the BoNT/A cleavage site scissile bond, purified NTP22 and NTP 23 α-SNAP-25 polyclonal antibodies were used to detectcleavage product using the cell-based activity assay,immunocytochemistry and immunoprecipitation as described in Example III.The cell-based cleavage assay, immunocytochemistry analysis andimmunoprecipitation analysis all indicated that NTP 22 and NTP 23α-SNAP-25 polyclonal antibodies did not cross-react with uncleavedSNAP-25. Thus both NTP 22 and NTP 23 have high binding specificity forthe SNAP-25₁₉₇ cleavage product that allows for the preferentialrecognition of this cleavage product relative to the SNAP-25₂₀₆uncleaved substrate. Affinity for the antigens can be determined usingSPR in the BiAcore as described in Example III.

Example IX Component and Condition Preparation for a Sandwich ELISA

The following example illustrates how to identify and prepare thecomponents and conditions necessary to perform a sandwich ELISA usefulfor conducting immuno-based methods of detecting retargetedendopeptidase activity by detecting a SNAP-25 cleavage product using anα-SNAP-25 monoclonal antibody specific for a SNAP-25 having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond.

1. Preparation of Cell Lysates from Cells Treated with Re-TargetedEndopeptidase.

To obtain a re-targeted endopeptidase treated cell lysate for analysis,a suitable density of cells from a stock culture of Neuro-2a was seededinto a T175 flask containing 50 mL of a serum-free medium containingMinimum Essential Medium, 2 mM GlutaMAX™ I with Earle's salts, 1×B27supplement, 1×N2 supplement, 0.1 mM Non-Essential Amino Acids, 10 mMHEPES. These cells were incubated in a 37° C. incubator under 5% carbondioxide until the cells differentiated, as assessed by standard androutine morphological criteria, such as growth arrest and neuriteextension (approximately 2 to 3 days). As a control, a suitable densityof cells from a stock culture of Neuro-2a was seeded into a T175 flaskcontaining 50 mL of an appropriate growth medium (Table 1). Theseundifferentiated control cells were grown in a 37° C. incubator under 5%carbon dioxide until 50% confluence was reached (approximately 18hours). The media from both differentiated and undifferentiated controlcultures was aspirated from each well and replaced with fresh mediacontaining either 0 (untreated sample) or 10 nM of a re-targetedendopeptidase. After an overnight incubation, the cells were washed andthe cells harvested by lysing in freshly prepared Triton X-100 LysisBuffer (50 mM HEPES, 150 mM NaCl, 1.5 mM MgCl₂, 1 mM EGTA, 1% TritonX-100) at 4° C. for 30 minutes with constant agitation. Lysed cells werecentrifuged at 4000 rpm for 20 min at 4° C. to eliminate debris using abench-top centrifuge. The protein concentrations of cell lysates weremeasured by Bradford assay.

2. Preparation and Identification of Sandwich ELISA Components.

To identify an appropriate capture antibody-detection antibody pair anECL sandwich ELISA analysis was conducted on twenty-six differentcombinations of capture and detection antibody pairs comprising elevendifferent α-SNAP-25 capture antibodies and seven different α-SNAP-25detection antibodies (Table 12). The α-SNAP-25 antibodies used were2E2A6 and 3C1A5 α-SNAP-25 mouse monoclonal antibodies disclosed in thepresent specification, SMI-81, MC-6050, and MC-6053 α-SNAP-25 mousemonoclonal antibodies disclosed in the present specification, NTP 23α-SNAP-25 rabbit polyclonal antibodies disclosed in the presentspecification, S9684 α-SNAP-25 rabbit polyclonal antibodies (Sigma, St.Louis, Mo.), H-50 α-SNAP-25 rabbit polyclonal antibodies (Santa CruzBiotechnology, Inc., Santa Cruz, Calif.), C-18 α-SNAP-25 goat polyclonalantibodies (Santa Cruz Biotechnology, Inc., Santa Cruz, Calif.), N-19α-SNAP-25 goat polyclonal antibodies (Santa Cruz Biotechnology, Inc.,Santa Cruz, Calif.), and SP12 α-SNAP-25 mouse polyclonal antibodies(Santa Cruz Biotechnology, Inc., Santa Cruz, Calif.).

To prepare the capture antibody solution, the α-SNAP-25 monoclonalantibodies contained in the ascites from hybridoma cell lines 2E2A6 and3C1A5 as well as the α-SNAP-25 MC-6050 and MC-6053 monoclonal antibodieswere purified using a standard Protein A purification protocol. Allother α-SNAP-25 antibodies were purchased as purified antibodies.

To prepare the detection antibody solution, the appropriate α-SNAP-25antibody was conjugated toRuthenium(II)-tris-bipyridine-(4-methysulfonate) NHS ester labelingreagent (Meso Scale Discovery, Gaithersburg, Md.) according to themanufacturer's instructions (Meso Scale Discovery, Gaithersburg, Md.).The conjugation reaction was performed by adding 30 μL of distilledwater reconstituted MSD SULFO-TAG™ stock solution to 200 μL of 2 mg/mLα-SNAP-25 polyclonal antibodies and incubating the reaction at roomtemperature for 2 hours in the dark. The labeled antibodies werepurified using a standard spin column protocol and the proteinconcentration determined using a standard colorimetric protein assay.The absorbance of the α-SNAP-25 antibody/MSD SULFO-TAG™ conjugate wasmeasured at 455 nm using a spectrophotometer to determine theconcentration in moles per liter. The detection antibody solution wasstored at 4° C. until needed.

To prepare the solid phase support comprising the capture antibody thatis specific for a SNAP-25 cleavage product, approximately 5 μL of theappropriate α-SNAP-25 monoclonal antibody solution (20 μg/mL in 1×PBS)is added to each well of a 96-well MSD High Bind plate and the solutionis allowed to air dry in a biological safety cabinet for 2-3 hours inorder to liquid evaporate the solution. The capture antibody-bound wellswere then blocked by adding 150 μL of Blocking Buffer comprising 2%Amersham Blocking Reagent (GE Life Sciences, Piscataway, N.J.) and 10%goat serum (VWR, West Chester, Pa.) at room temperature for 2 hours.Blocked plates were sealed and stored at 4° C. until needed.

To detect the presence of a cleaved SNAP-25 cleavage product by ECLsandwich ELISA analysis, the Blocking Buffer from stored plates wasaspirated from the wells, 25 μL of a lysate from cells treated withre-targeted endopeptidase, as described above, was added to each welland the plates were incubated at 4° C. for overnight. Plate wells werewashed three times by aspirating the cell lysate and rinsing each wellthree times with 200 μL 1×PBS, 0.1% TWEEN-20® (polyoxyethylene (20)sorbitan monolaureate). After washing, 25 μl of 5 μg/mL detectionantibody solution comprising 2% Amersham Blocking Reagent in 1×PBS, 0.1%TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate) was added to eachwell, the plate was sealed, and the sealed plate was incubated at roomtemperature at room temperature for 1 hour with shaking. After detectionantibody incubation, the wells were washed three times with 200 μL1×PBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate).After washing 150 μL of 1× Read Buffer (Meso Scale Discovery,Gaithersburg, Md.) was added to each well and the plates were read usinga SECTOR™ Imager 6000 Image Reader (Meso Scale Discovery, Gaithersburg,Md.). A ratio was calculated by dividing the signal obtained at the 10nM dose for each antibody-pair by the signal obtained at the 0 nM dosefor each antibody-pair (Table 24). These results indicated that amongthe twenty-six different combinations of antibody pairs tested, onlythree antibody pairs had signal-to-noise ratios above 10:1 for thehigher dose tested: Pair No. 1 (2E2A6 mouse mAb and S9684 rabbit pAb),Pair No. 4 (3C1A5 mouse mAb and S9684 rabbit pAb), and Pair No. 18(S9684 rabbit pAb and 2E2A6 mouse mAb). Antibody Pair 1 was chosen forfurther assay development.

TABLE 24 Screening of α-SNAP-25 Antibody Combinations Detection SNAP-25Detection SNAP- Signal/Noise Antibody Detection cleavage 25 uncleavedRatio Pair No. Capture Antibody Antibody product substrate (10 nM/0 nM)1 2E2A6 mouse mAb S9684 rabbit pAb Yes No 26.6:1  2 2E2A6 mouse mAb N-19goat pAb Yes No 7.3:1 3 2E2A6 mouse mAb H-50 rabbit pAb Yes No 0.9:1 43C1A5 mouse mAb S9684 rabbit pAb Yes No 12.1:1  5 3C1A5 mouse mAb N-19goat pAb Yes No 1.9:1 6 3C1A5 mouse mAb H-50 rabbit pAb Yes No 0.9:1 7C-18 goat pAb S9684 rabbit pAb No No 0.8:1 8 C-18 goat pAb N-19 goat pAbNo No 0.9:1 9 C-18 goat pAb H-50 rabbit pAb No No 0.9:1 10 H-50 rabbitpAb 2E2A6 mouse mAb Yes No 0.9:1 11 H-50 rabbit pAb C-18 goat pAb No No1.0:1 12 N-19 goat pAb 2E2A6 mouse mAb Yes No 0.9:1 13 N-19 goat pAbC-18 goat pAb No No 1.1:1 14 NTP 23 rabbit pAb N-19 goat pAb Yes No1.2:1 15 NTP 23 rabbit pAb C-18 goat pAb No No 1.1:1 16 NTP 23 rabbitpAb SP12 mouse pAb Yes No 1.3:1 17 NTP 23 rabbit pAb H-50 rabbit pAb YesNo 1.1:1 18 S9684 rabbit pAb 2E2A6 mouse mAb Yes No 21.3:1  19 S9684rabbit pAb C-18 goat pAb No No 0.7:1 20 S9684 rabbit pAb SMI-81mouse YesYes 1.2:1 mAb 21 SMI-81 mouse mAb S9684 rabbit pAb Yes Yes 1.1:1 22SMI-81 mouse mAb N-19 goat pAb Yes Yes 1.0:1 23 SMI-81 mouse mAb C-18goat pAb No No 0.8:1 24 SP12 mouse pAb C-18 goat pAb No No 1.0:1 25MC-6050 mouse S9684 rabbit pAb Yes Yes 5.0:1 mAb 26 MC-6053 mouse S9684rabbit pAb Yes Yes 7.1:1 mAb

Example X Immuno-Based Method of Detecting Re-Targeted EndopeptidaseHaving a BoNT/A Light Chain Enzymatic Activity Using ECL Sandwich ELISA

The following example illustrates immuno-based methods of detectingretargeted endopeptidase activity by detecting a SNAP-25 cleavageproduct using an α-SNAP-25 monoclonal antibody specific for a SNAP-25cleavage product having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond by ECL sandwich ELISA.

To prepare a lysate from cells treated with a re-targeted endopeptidasehaving BoNT/A light chain enzymatic activity, a suitable density ofcells from an established cell line was plated into the wells of 96-welltissue culture plates containing 100 μL of the appropriate media. Thesecells were incubated in a 37° C. incubator under 5% carbon dioxide forabout 24 hours. The media from the cells was aspirated from each welland replaced with fresh media containing either 0 (untreated sample) orone of the doses determined from a dose-response experiment for thatre-targeted endopeptidase. After 24 hours incubation, the cells werewashed and harvested.

To prepare the α-SNAP-25 capture antibody solution, the α-SNAP-25monoclonal antibody contained in the ascites from hybridoma cell line2E2A6 was purified using a standard Protein A purification protocol Toprepare the α-SNAP-25 detection antibody solution, α-SNAP-25 rabbitpolyclonal antibody S9684 (Sigma, St. Louis, Mo.) was conjugated toRuthenium(II)-tris-bipyridine-(4-methysulfonate) NHS ester labelingreagent (Meso Scale Discovery, Gaithersburg, Md.) according to themanufacturer's instructions (Meso Scale Discovery, Gaithersburg, Md.).The conjugation reaction, purification of labeled α-SNAP-25 antibody,concentration determination and storage were as described in Example VI.

To prepare the solid phase support comprising the capture antibody thatis specific for a SNAP-25 cleaved product, approximately 5 μL ofα-SNAP-25 monoclonal antibody 2E2A6 solution (20 μg/mL in 1×PBS) wasadded to each well of a 96-well MSD High Bind plate and the solution isallowed to air dry in a biological safety cabinet for 2-3 hours in orderto liquid evaporate the solution. The capture antibody-bound wells werethen blocked and used directly to detect retargeted endopeptidaseactivity.

To detect the presence of a cleaved SNAP-25 product by ECL sandwichELISA analysis, the Blocking Buffer from stored plates was aspiratedfrom the wells, 25 μL of a lysate from cells treated with re-targetedendopeptidase was added to each well and the plates were incubated at 4°C. for overnight. Plate wells were washed three times by aspirating thecell lysate and rinsing each well three times with 200 μL 1×PBS, 0.1%TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate). After washing,25 μL of 5 μg/mL detection antibody solution comprising 2% AmershamBlocking Reagent in 1×PBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitanmonolaureate) was added to each well, the plate was sealed, and thesealed plate was incubated at room temperature at room temperature for 1hour with shaking. After detection antibody incubation, the wells werewashed three times with 200 μL 1×PBS, 0.1% TWEEN-20® (polyoxyethylene(20) sorbitan monolaureate). After washing 150 μL of 1× Read Buffer(Meso Scale Discovery, Gaithersburg, Md.) was added to each well and theplates were read using a SECTOR™ Imager 6000 Image Reader (Meso ScaleDiscovery, Gaithersburg, Md.). The collected data was analyzed and theEC₅₀ calculated as described in Example VI. For opioid re-targetedendopeptidases, these results indicated that on average 1.0 nM of Noc/Aat the EC₅₀ was detected (a range of about 0.3 nM to about 2.0 nM) witha signal-to-noise ratio for the lower asymptote of about 15:1 to about20:1 and a signal-to-noise ratio for the upper asymptote of about 180:1to about 300:1.

Example XI Immuno-Based Method of Detecting Re-Targeted EndopeptidaseActivity Using CL Sandwich ELISA

The following example illustrates immuno-based methods of detectingretargeted endopeptidase activity by detecting a SNAP-25 cleavageproduct using an α-SNAP-25 monoclonal antibody specific for a SNAP-25having a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond by CL sandwich ELISA.

Lysate from cells treated with a re-targeted endopeptidase and theα-SNAP-25 capture antibody solution will be prepared as described inExample VII.

To prepare the α-SNAP-25 detection antibody solution, α-SNAP-25polyclonal antibody S9684 (Sigma, St. Louis, Mo.) will be conjugated toHorseradish peroxidase (HRP) according to the manufacturer'sinstructions (Pierce Biotechnology, Inc., Rockford, Ill.). Theconjugation reaction will be performed by adding to 500 μL of 1 mg/mLα-SNAP-25 polyclonal antibodies to a vial containing lyophilizedactivated peroxidase, mixing the components, and then adding 10 μL ofsodium cyanoborohydride. This reaction mixture will be incubated at roomtemperature for 1 hour in a fume hood. After quenching the reaction, thelabeled antibodies will be purified using a standard spin columnprotocol and the protein concentration will be determined using astandard colorimetric protein assay. The absorbance of the α-SNAP-25polyclonal antibody/HRP conjugate will be measured at 455 nm using aspectrophotometer to determine the concentration in moles per liter. Theα-SNAP-25 detection antibody solution will be stored at 4° C. untilneeded.

To prepare the solid phase support comprising the α-SNAP-25 captureantibody that is specific for the SNAP-25 cleaved product, approximately100 μL of α-SNAP-25 monoclonal antibody 2E2A6 solution (1 mg/mL in1×PBS) will be added to each well of a 96-well Greiner white plate andthe plates will be incubated at 4° C. overnight, and then any excessantibody solution will be discarded. The capture antibody-bound wellswill then be blocked by adding 150 μL of Blocking Buffer comprising 2%Amersham Blocking Reagent (GE Life Sciences, Piscataway, N.J.) and 10%goat serum (VWR, West Chester, Pa.) at room temperature for 1 hour. Theblocking buffer will be discarded and the plates will be blotted dry onpaper towels by inverting and tapping. The capture antibody-bound wellswill then be blocked and will be used directly to detect retargetedendopeptidase activity.

To detect the presence of a cleaved SNAP-25 product by CL sandwich ELISAanalysis, 50 μL of a lysate from cells treated withretargeted-endopeptidase will be added to each well, the plate will besealed, and the sealed plate will be incubated on a shaker rotating at500 rpm at 4° C. for 2-4 hours to overnight. Plate wells will be washedthree times by aspirating the cell lysate and rinsing each well threetimes with 200 μl 1×PBS, 0.05% TWEEN-20® (polyoxyethylene (20) sorbitanmonolaureate). After washing, 100 μL of 1 mg/mL α-SNAP-25 polyclonalantibody/HRP detection antibody solution comprising 2% Amersham BlockingReagent in 1×PBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitanmonolaureate) will be added to each well, the plate will be sealed, andthe sealed plate will be incubated on a shaker rotating at 650 rpm atroom temperature for 1 hour. After detection antibody incubation, thewells will be washed three times with 200 μl 1×PBS, 0.05% TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate). After washing 100 μl ofSuperSignal ELISA Pico 1:1 mixture (Pierce Biotechnology, Inc.,Rockford, Ill.) will be added to each well and the plates will be readusing a luminometer (Molecular Devices, Sunnyvale, Calif.) at 395 nm.The collected data will be analyzed and the EC₅₀ will be calculated asdescribed in Example VI.

Example XII Immuno-Based Method of Detecting Re-Targeted EndopeptidaseActivity Using Multiplex ECL Sandwich ELISA

The following example illustrates multiplex immuno-based methods ofdetecting retargeted endopeptidase activity by detecting a SNAP-25cleavage product using an α-SNAP-25 monoclonal antibody specific for aSNAP-25 cleavage product and a second antibody pair for a differentprotein.

A re-targeted endopeptidase potency assay can be performed using amultiplex ECL sandwich ELISA. Such an assay is described in companionpatent application Ester Fernandez-Salas, et al., Immuno-Based BotulinumToxin Serotype A Activity Assays, U.S. patent application Ser. No.12/403,531, which is hereby incorporated by reference in its entirety,and can be used using the cell lines and re-targeted endopepitases andthe corresponding cell lines disclosed in the present specification.

Example XIII Immuno-Based Method of Detecting Re-Targeted EndopeptidaseActivity Using Multiplex EC Sandwich ELISA

The following example illustrates multiplex immuno-based methods ofdetecting retargeted endopeptidase activity by detecting a SNAP-25cleavage product using an α-SNAP-25 monoclonal antibody specific for aSNAP-25 cleavage product and a second antibody pair for a differentprotein.

A re-targeted endopeptidase potency assay can be performed using amultiplex EC sandwich ELISA. Such an assay is described in companionpatent application Ester Fernandez-Salas, et al., Immuno-Based BotulinumToxin Serotype A Activity Assays, U.S. patent application Ser. No.12/403,531, which is hereby incorporated by reference in its entirety,and can be used using the cell lines and re-targeted endopepitases andthe corresponding cell lines disclosed in the present specification.

Example XIV Immuno-Based Method to Detect Nanomolar Amounts ofRetargeted Endopeptidases

The following example illustrates how to perform immuno-based methods ofdetecting Nanomolar amounts of retargeted endopeptidase activity.

1. Immuno-Based Method of Detecting Retargeted Endopeptidases Using ECLSandwich ELISA.

To prepare a lysate from cells treated with a retargeted endopeptidase,approximately 50,000 to 150,000 cells from an established cell linesuitable for the assay were plated into the wells of 96-well tissueculture poly-D-lysine plates containing 100 μL of the appropriate media(see Examples I and II). These cells were incubated in a 37° C.incubator under 5% carbon dioxide for 24 hours. The media from the cellswas aspirated from each well and replaced with fresh media containingeither 0 (untreated sample) and the appropriate dose response asdescribed for each retargeted endopeptidase in this application. After a24 hour incubation, the cells were washed and harvested or incubated foran additional two days without retargeted endopeptidase beforeharvesting. To harvest the cells, the medium was aspirated, washed with1×PBS, and lysed by adding 30 μL of Lysis Buffer comprising 50 mM HEPES,150 mM NaCl, 1.5 mM MgCl₂, 1 mM EGTA, 1% Triton X-100 to each well, andthe plate incubated on a shaker rotating at 500 rpm for 30 minutes at 4°C. The plate was centrifuged at 4000 rpm for 20 minutes at 4° C. topellet cellular debris and the supernatant was transferred to a captureantibody coated 96-well plate to perform the detection step.

The α-SNAP-25 capture antibody solution, the α-SNAP-25 detectionantibody solution, and the solid phase support comprising the captureantibody that is specific for a SNAP-25 cleaved product were prepared asdescribed in Example VII.

To detect the presence of a cleaved SNAP-25 product by ECL sandwichELISA analysis, the Blocking Buffer from stored plates was aspirated,25-30 μL of a lysate from cells treated with retargeted endopeptidasewas added to each well and the plates were incubated at 4° C. for either2 hours or 24 hours. Plate wells were washed three times by aspiratingthe cell lysate and rinsing each well three times with 200 μL 1×PBS,0.1% TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate). Afterwashing, 25 μL of 5 μg/mL α-SNAP-25 detection antibody solutioncomprising 2% Amersham Blocking Reagent in 1×PBS, 0.1% TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate) was added to each well, theplate was sealed, and the sealed plate was incubated at room temperaturefor 1 hour with shaking. After α-SNAP-25 detection antibody incubation,the wells were washed three times with 200 μL 1×PBS, 0.1% TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate). After washing, the plateswere processed, collected data was analyzed, and the EC₅₀ calculated asdescribed in Example VI. These results indicated that on average 1.0 nMof Noc/A at the EC₅₀ was detected when using SK-N-DZ clonal cell line #3cells (a range of about 0.3 nM to about 2.0 nM) with a signal-to-noiseratio for the upper asymptote of about 20:1 to about 300:1. Moreover, onaverage 3.7 nM of Noc/A at the EC₅₀ was detected when using AGN P33clonal cell line #6 cells (a range of about 2.0 nM to about 5.5 nM) witha signal-to-noise ratio for the upper asymptote of about 20:1 to about500:1. For the SK12 cells that are specific for the retargetedendopeptidase containing a dynorphin A ligand, on average 8.4 nM ofDyn/A at the EC₅₀ was detected when using SK12 cells (a range of about4.5 nM to about 10.0 nM) with a signal-to-noise ratio for the upperasymptote of about 10:1 to about 20:1. Additionally, on average 8.8 nMof TVEMP-galanin at the EC₅₀ was detected when using Neuro-2a clonalcell line #7 cells (a range of about 5.0 nM to about 15.5 nM) with asignal-to-noise ratio for the upper asymptote of about 20:1 to about200:1. This method can also be performed in a multiplex fashion asdescribed in Example IX.

2. Immuno-Based Method of Detecting Retargeted Endopeptidases Using CLSandwich ELISA.

Lysate from cells treated with a retargeted endopeptidase and theα-SNAP-25 capture antibody solution will be prepared as described inExample VII. The α-SNAP-25 detection antibody solution and solid phasesupport comprising the capture antibody that is specific for a SNAP-25cleaved product will be prepared as described in Example VIII.

To detect the presence of a cleaved SNAP-25 product by CL sandwich ELISAanalysis, 100 μL of a lysate from cells treated with a retargetedendopeptidase will be added to each well, the plate will sealed, and thesealed plate will be incubated on a shaker rotating at 500 rpm at 4° C.for either 2 hours or 24 hours. Plate wells will be washed three timesby aspirating the cell lysate and rinsing each well three times with 200μL 1×PBS, 0.05% TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate).After washing, 100 μL of 1 mg/mL α-SNAP-25 polyclonal antibody/HRPdetection antibody solution comprising 2% Amersham Blocking Reagent in1×PBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate) willbe added to each well, the plate will be sealed, and the sealed platewill be incubated on a shaker rotating at 650 rpm at room temperaturefor 1 hour. After detection antibody incubation, the wells will bewashed three times with 200 μL 1×PBS, 0.05% TWEEN-20® (polyoxyethylene(20) sorbitan monolaureate). After washing 100 μL of SuperSignal ELISAPico 1:1 mixture (Pierce Biotechnology, Inc., Rockford, Ill.) will beadded to each well and the plates will be read using a luminometer(Molecular Devices, Sunnyvale, Calif.) at 395 nm. The collected datawill be analyzed and the EC₅₀ will be calculated as described in ExampleVI. This method can also be performed in a multiplex fashion asdescribed in Example IX.

Example XV Immuno-Based Method to Detect Neutralizingα-Retargeted-Endopeptidase Antibodies

The following example illustrates how to perform an immuno-based methodthat can detect the presence of neutralizing α-Noc/A antibodies.

Noc/A, is currently being evaluated for treating painful conditions,some of them chronic. With repeated long-term treatment of Noc/A, apatient may develop neutralizing α-Noc/A antibodies to the retargetedendopeptidase leading to immunoresistance. Neutralizing α-Noc/Aantibodies will inhibit retargeted endopeptidase activity by stoppingthe retargeted endopeptidase's uptake into neuronal and other targetcells by binding to the targeting ligand and/or the translocation domain(H_(N)) of the retargeted endopeptidase. There is not established assayto determine the presence of the neutralizing α-Noc/A antibodies inpatient's blood. It would be more cost and time efficient if acell-based assay could be developed to detect neutralizing antibodies inpatients treated with retargeted endopeptidases.

To detect the presence or absence of neutralizing α-Noc/A antibodies,the immuno-based methods of determining retargeted endopeptidaseactivity disclosed in the present specification can be used. One way isto determine the amount of SNAP-25 cleavage product present aftertreatment with various concentrations of Noc/A using a Western blotdetection method, the other way was to use an ECL sandwich ELISAdetection method.

To prepare a sample comprising neutralizing α-Noc/A antibodies, serumwas isolated from blood of a monkey immunized with Noc/A and theantibodies were affinity purified. Rabbits were also immunized with thenociceptin variant peptide, the targeting ligand present in the Noc/Amolecule, their serum collected, and the antibodies affinity purified(anti-nociceptin polyclonal antibodies).

To prepare a lysate from cells treated with a sample comprising Noc/A,SK-N-DZ clonal cell line #3 cells and AGN P33 clonal cell line #6 cellswere seeded in poly-D-lysine 96-well plates for 16-18 hours.Anti-nociceptin pAb at 0-3 μg/mL was diluted in RPMI SFM (with N2, B27,and NGF supplements) containing 1 nM of Noc/A and the mix waspre-incubated at room temperature for 1 hour. Then the solutions wereadded to the cells and incubated for 24 h before performing the ECLELISA assay. This anti-nociceptin variant antibody totally blocked 1 nMNoc/A uptake at 1 μg/mL (>90% inhibition) on both cell lines. Anti-Noc/Amonkey polyclonal antibody was also assayed these cell lines. Cells wereplated in a 96-well poly-D-lysine plate at 100,000 cells per well for 24hours in RPMI growth media supplemented with N2, B27, and NGF.Anti-Noc/A polyclonal antibodies at 0-20 μg/mL was diluted in mediacontaining 1 nM Noc/A and the mix was pre-incubated at room temperaturefor 1 h. Then the mix was added to the cells and incubated for 24 hbefore performing the ECL ELISA assay. Up to 60% inhibition was seen atthe higher concentrations of 6-20 μg/mL of anti-Noc/A pAb on the SK-N-DZcell line and about 30% on the AGN P33 clonal cell line #6 cell line.This may due to the fact that the anti-Noc/A polyclonal antibodies isnot specific to the binding site and contains other antibodies that bindother parts of the molecule producing only partial blocking at theconcentrations tested. Higher concentrations maybe needed to achievecomplete blocking.

To detect the presence of a cleaved SNAP-25 product by Western blotanalysis, the media will aspirated from each well, the cells suspendedin 50 μL of SDS-PAGE loading buffer, and then heated to 95° C. for 5minutes. An aliquot from each harvested sample will be analyzed byWestern blot as described in Example I, except that harvested sampleswill be separated by SDS-PAGE using 12% 26-well Criterion gels (Bio-RadLaboratories, Hercules, Calif.), and the rabbit polyclonal α-SNAP-25₁₉₇antibody serum will be used as the primary antibody (see Example V). Theresults will reveal the lowest concentration of retargeted endopeptidasethat will produce a detectable band of SNAP-25 cleavage product in theWestern blot.

To detect the presence of a cleaved SNAP-25 product by ECL SandwichELISA, the media was removed from each well and the cells were lysed asdescribed in Example VI. The α-SNAP-25 capture antibody solution, theα-SNAP-25 detection antibody solution, and the α-SNAP-25 solid phasesupport were prepared as described in Example VIII. Supernatants weretransferred to the α-SNAP-25 solid phase support and an ECL sandwichELISA assay was performed as detailed in Example VI. The collected datawas analyzed and the EC₅₀ calculated as described in Example VI, exceptthat the EC₅₀ is the serum dilution needed to inhibit the activity ofthe retargeted endopeptidase to ½ its maximum and the ratio of maximalsignal (Signal_(Max)) to minimum signal (Signal_(Min)) was obtained bydividing the SNAP-25 cleavage product signal obtained with the highestdilution of antibody by the signal obtained with the lowest antibodydilution.

The results indicate that the presence of neutralizing α-Noc/Aantibodies in monkey serum and the presence of α-nociceptin variantantibodies from rabbit could be detected. The activity of the Noc/Amolecule incubated in affinity purified antibodies from the immunizedanimal decreased as the antibody dilution decreased. The same assay willbe performed with the Dyn/A and the TVEMP-galanin compounds utilizingthe cell lines specific for each compound to be tested.

Example XV Development of a Cell-Based Assay for a Galanin Re-TargetedEndopeptidase

The following example illustrates how to identify established cell linespossessing the re-targeted endopeptidase uptake capacity required todevelop a cell-based potency assay.

1. Growth of Stock Culture of Candidate Cell Lines.

To grow the cell lines, a suitable density of cells from the cell linebeing tested were plated in a 162 cm² tissue culture flask containing 30mL of a suitable growth medium (see Table 25), and grown in a 37° C.incubator under 5% or 10% carbon dioxide until cells reached the desireddensity.

TABLE 25 Summary table of all cell lines and their respective media.Complete Media (CM) Serum Free media (SFM) All from Invitrogen (unlessAll from Invitrogen, (unless Cell type; description; source otherwisespecified) otherwise specified) SiMa (Human neuroblastoma cell RPMI 1640(90%) RPMI 1640 (90%) line, DSMZ# ACC 164, Fetal Bovine Serum (FBS, 10%)NEAA (0.1 mM), Braunschweig, Germany) NEAA (0.1 mM), HEPES (10 mM), SiMaH1 (cloned cell line from HEPES (10 mM), Sodium Pyruvate (1 mM) SiMacells) Sodium Pyruvate (1 mM) Penicillin (100 U per ml) Penicillin (100U per ml) Streptomycin (100 μg per ml) Streptomycin (100 μg per ml), N2supplement (1x) B27 supplement (1x) Neuro-2a Earle's MEM (90%) EMEM(90%) (Mouse neuroblastoma: Fetal Bovine Serum 10%) NEAA (0.1 mM),(ATCC#CCI131, Manassas, VA,) NEAA (0.1 mM), HEPES (10 mM), HEPES (10mM), Sodium Pyruvate (1 mM), Sodium Pyruvate (1 mM), Penicillin (100 Uper ml), Penicillin (100 U per ml), Streptomycin (100 μg per ml)Streptomycin (100 μg per ml) PC-12 RPMI 1640 (90%) Differentiationmedia: Rat Pheochromocytoma Dialyzed FBS (5%) RPMI 1640 (90%) (ATCC #CRL-1721) Horse serum (10%) HEPES (10 mM) HEPES (10 mM) Sodium Pyruvate(1 mM) Sodium Pyruvate (1 mM) D-glucose (0.5%, Sigma) D-glucose (0.5%,Sigma) Penicillin (100 U per ml); Penicillin (100 U per ml);Streptomycin (100 μg per ml) Streptomycin (100 μg per ml) N2 supplement(1x) N2 supplement (1x) Bovine serum albumin (0.2% w/v) NGF (50 ng perml, Promega) P19 Alpha MEM (90%) Alpha MEM (90%) Mouse embryoniccarcinoma Bovine Calf Serum (7.5%) FBS (2.5%) (ATCC #CRL-1825) FBS(2.5%) Penicillin (100 U per ml); Penicillin (100 U per ml);Streptomycin (100 μg per ml) Streptomycin (100 μg per ml) NEAA:Non-Essential Amino Acids, MEM: Minimum Essential Media. DMEM:Dulbecco's MEM. EMEM—Earle's MEM. Please note PC-12 cells weredifferentiated in differentiation media and not SFM.

2. Screening of Commercial Cell Lines for Sensitivity to GalaninTVEMP-Galanin Compounds

Commercial cell lines were screened for their sensitivity toTVEMP-galanin compounds as measured by the cleavage of SNAP25 aftertreatment with the corresponding compounds. Various TVEMP-galanincompounds were used for screening and testing. PC-12, Neuro-2a, SiMa,and P19 cells were plated in serum free media for three days or in CMfor one day. These differentiated and naïve cells were treated for 18hours with TVEMP-galanin Batch A at concentrations of 0 and 75 nM.TVEMP-galanin Batch A showed activity in both PC-12 and Neuro-2a cellsas seen by the increased presence of cleaved SNAP25, and Neuro-2a cellsin the differentiated condition are more sensitive to TVEMP compoundswith galanin ligand, than the naïve cells. The rank order in activity ofthe cells shows PC-12 have the most activity, followed by Neuro-2a andfinally SiMa cells. It was necessary to determine if the uptake wasspecific for these galanin-retargeted compounds and therefore it wasimportant to test the cells with other compounds that do not contain thegalanin ligand. Noc/A is a retargeted compound which contains anociceptin variant ligand, and LH_(N)/A (a negative control) a compoundthat lacks the binding domain. The uptake of LH_(N)/A is non-specificand should have significantly lower activity than the TVEMP-galanincompound if the cell line possess specific uptake for the retargetedcompound. The Noc/A compound has been shown previously to have specificuptake in the SiMa cells and will be used as a baseline to test the celllines. A favorable cell line should have low uptake of the LH_(N)/A andthe Noc/A compound and high uptake of the TVEMP-galanin compound. Table26 displays the results from this experiment.

TABLE 26 Screening of PC-12, Neuro-2a, and SiMa cells at differentconditions using TVEMP-galanin. TVEMP-galanin TVEMP-galanin Batch ABatch B LH_(N)/A Noc/A Conc. (mg/mL) 0.168 0.175 1.63 1.00 EC₅₀ PC-12,naïve  73.4 ± 10.7 105.6 ± 16.0 >200 72.9 ± 26.9 Values SiMa, naïve138.6 ± 43.9 133.8 ± 24.2 >300 48.3 ± 18.1 (nM) Neuro-2a, naïve 122.4 ±15.7   116 ± 17.5 >200 >150 SiMa, Dif O/N >400 >150 >400 16.1 ± 11.9Neuro-2a Dif 4 d 34.5 ± 7.5 39.7 ± 5.6 105.9 ± 44.3  SiMa, Dif 4 d 101.8± 20.5 65.3 ± 7.8 >150 88.7 ± 23.3 TVEMP-galanin Batches A and B, andLH_(N)/A and Noc/A controls testing on various cell lines andgrowth/differentiation conditions. Summary chart showing details of eachcompound tested plus EC₅₀ values.

The results show that TVEMP-galanin Batch A and TVEMP-galanin Batch Bhad plots or EC₅₀ values that were either similar to, or only 1-2 foldmore active than the negative controls in the cell lines tested. Thisdata implies that the native cells are not sensitive enough and thatthese cells will have to be transfected with the plasmids encodinggalanin receptor proteins GalR1 or GalR2 receptors.

3. Stable Transfection of PC-12, Neuro-2a, and SiMa Cells with GalR.

One day before transfection, cells were seeded at densities of 0.5×10⁶cells/well in either a 6-well Collagen IV coated plate (Cat#354554: BDBiosciences) (SiMa, PC-12) or a 6 well Costar plate (Cat#3516: Corning)(Neuro-2a). Transfections were performed by diluting 12 μl ofLipofectamine™ 2000 (Cat #52758, Invitrogen) in 250 μl Opti-MEM® IReduced Serum Medium (Cat#3195, Invitrogen) followed by incubation atroom temperature for 5 min. Four micrograms of GalR plasmid DNA wasmixed with 0.4 μg pAdVantage™ vector (1 mg per ml, Cat#E1711, Promega)in 250 μl Opti-MEM® I Reduced Serum Media for 5 minutes. After 5 minutesof incubation, the diluted Lipofectamine™ 2000 and the diluted plasmidsDNA were mixed and incubated for an additional 20 min at roomtemperature, for complex formation. In the meantime, the cells werewashed with OPTI-MEM® and 0.5 ml OPTI-MEM® was added to each well. Afterthe 20 minute incubation, 0.5 ml containing the complexes of dilutedLipofectamine™ 2000 and diluted plasmids DNA was carefully added to thewells containing cells in 0.5 ml OPTI-MEM®. The plate was incubated at37° C. for 5 hours, after which 1 ml of complete media was added. Thenext day, the medium was replaced with growth media for 48 hours. On day4, after cells were recovered from the transfection, the growth mediawas replaced with fresh growth media containing Geneticin® (Cat #10131:Invitrogen) at 0.5 mg per ml (1:100 dilution) and incubated for anadditional 3 days. On day 7 post transfection, the cells weretransferred to a 75 cm Collagen IV flask (Cat#35423: BD Biosciences)containing growth medium and geneticin (0.5 mg per ml, 1:100 dilution).On this transfer, approximately 90% of the cells were dead and wereremoved during the media change. Growth media containing geneticin (0.5mg per ml, 1:100 dilution) was changed every two days till day 21.

For the selection of stable cells able to take up galanin TVEMPcompounds, the parameters were to screen for clones that produced thehighest percentage of SNAP25 cleavage with TVEMP-galanin treatment inthe ECL Sandwich ELISA using monoclonal 2E2A6 coated plates for captureand polyclonal SNAP25 (Sigma Cat # S9684) sulfotagged antibody fordetection. The EC₅₀ values in Table 27 show that TVEMP-galanin Batch Dexhibits at least 10-fold greater uptake than the negative control inthe SiMa and Neuro-2a cells transfected with GalR1 and GalR2, and only2-4 fold greater uptake in transfected PC-12 cells. Since the PC-12transfected cells seem to have lower sensitivity and specificity thanthe SiMa and Neuro-2a cells they will not be cloned. Also, since thegalanin 1-16 mer ligand in the TVEMP-Galanin compounds binds to GALR1receptor with more affinity than the GALR2, only cells transfected withGALR1 will be cloned. The figure also shows that TVEMP-galanin Batches Cand D exhibit 9-10 fold greater uptake than both LH_(N)/A and theretargeted nociceptin compound TVEMP-nociceptin in the Neuro-2a GalR1.

TABLE 27 Test of stably transfected but non-clonal populations of SiMa,Neuro-2a, and PC12 transfected with GalR1 or GalR2 receptors TVEMP-TVEMP- TVEMP- galanin C galanin D LH_(N)/A nociceptin Conc. (mg/mL)1.260 0.303 1.46 1.00 EC₅₀ SiMa GalR1 36.2 ± 8.6 >300 Values SiMa GalR226.6 ± 6.7 >300 (nM) PC-12 GalR1  64.1 ± 19.5 202.7 PC-12GalR2 >150 >300 Neuro-2a 32.2 ± 3.3 40.8 ± 6.0 >300 >300 GalR1 Neuro-2a35.2 ± 3.1 46.0 ± 6.1 >300 >300 GalR2

The non-clonal selected populations are not a good population of cellsto use on a regular basis because they contain a mix of cells expressingdifferent levels of receptor and these populations can change over time.To obtain stable cell lines derived from single cells, a dilutionalcloning approach was initiated. On day 21, the transfected cells weretrypsinized, needle-dissociated and counted. The remaining transfectedcell lines were frozen for future use. The cells were serially dilutedto 10 cells per ml in growth media containing geneticin (0.5 mg per ml,1:100 dilution). Either 2×96-well Collagen IV coated plates (SiMa,PC-12) or 2×96-well Costar plates (Neuro-2a) were plated at 100 μl perwell to achieve 1 cell per well density. The plates were returned to theincubator and left untouched for two weeks for colony formation. Aftertwo weeks (day 35), the wells were carefully checked for the presence ofsingle colonies formed on the bottom of the well (the entire well wascarefully checked for multiple colonies). When a well was identifiedwith a single cluster of cells, that entire well was carefullyscrutinized to make sure that one and only one cluster of cells waspresent. A picture of that single cluster was taken. If there were anyqueries about additional clusters, the well was not selected. On day 36,the clones that were selected were detached with TrypLE and 0.5 ml ofcomplete media containing geneticin (0.5 mg per ml, 1:100 dilution) wasadded to stop the trypsin reaction. This entire volume was transferredto 6-well plates and further diluted with 3.0 ml additional completemedia containing geneticin (0.5 mg per ml, 1:100 dilution). The cloneswere allowed to grow to 90% confluence, then trypsinized again andtransferred to 75 cm Collagen IV or Costar flasks with 10.0 ml completemedia containing geneticin (0.5 mg per ml, 1:100 dilution). Once thecells were 90% confluent again, the cells were used to either fill threecryovials for frozen storage or used for screening in the ELISA assayfor galanin retargeted compounds.

The reference compound TVEMP-galanin Batch C was used to test theseclones using two operators performing independent tests. The SiMa GalR1clones grew slowly and were not available for testing at this time.Fortunately, the Neuro-2a clones grew faster, and soon sufficientquantities of 8 of the 12 clones were available for testing. TheseNeuro-2a GalR1 clonal cells were tested with a full dose range ofTVEMP-galanin compounds (0-300 nM) and the results of nine of theseclones is shown below. The remaining four clones grew very slowly andwere not tested. The selected but non-clonal parental cells were platedalong with the clones to use as a benchmark. Table 28 shows the activityof each of the eight clones together with the selected non-clonalNeuro-2a GalR1 cells, when tested with TVEMP-galanin compound. Out ofthe eight clones tested, only clones #4, 7 and 12 showed good uptake ofthe TVEMP-galanin compound with acceptable EC₅₀ values. Neuro-2aGalR1clones #1, 3 and 10 did not take up the TVEMP-galanin compound,while clones #5, 11 and 13 together with the non-clonal populationgenerated very high EC₅₀ values and no further testing was done withthese cells.

TABLE 28 Results of screening Neuro-2a GalR1 single-cell derived cloneswith the TVEMP-galanin Batch C. EC50 ± Std. error (nM) Plate Cell typeOperator 1 Operator 2 1 N2A Non-clonal 82.1 ± 9.6  92.0 ± 10.8 1 N2AGALR1 Clone #1 >300 >300 1 N2A GALR1 Clone #3 >300 >300 1 N2A GALR1Clone #4 39.7 ± 3.4 39.4 ± 6.6 2 N2A Non-clonal  211.2 ± 167.7 116.0 ±26.8 2 N2A GALR1 Clone #5 202.6 ± 82.9 113.0 ± 18.1 2 N2A GALR1 Clone #723.1 ± 3.3 15.5 ± 1.8 2 N2A GALR1 Clone #10 >300 >300 3 N2A GALR1 Clone#7 20.3 ± 1.6 38.0 ± 6.3 3 N2A GALR1 Clone #11 270.0 ± 243  247.0 ± 101 3 N2A GALR1 Clone #12 43.2 ± 5.2  57.5 ± 14.3 3 N2A GALR1 Clone #13144.1 ± 143  184.7 ± 15.6

4. Characterization of GalR1 Expression in the Clonal Cell Lines

The screening of the clones showed that only clones #4, 7, and 12 aremore sensitive than the non-clonal cells. Messenger RNA (mRNA) wasextracted from these 3 clones as well as the non-transfected parentaland stably transfected non-clonal Neuro-2a cells for characterization byRT-PCR using the RT-PCR conditions described in Example V and theprimers described in Table 29.

TABLE 29 Specific GALR1 and GALR2 primers Name Sequence SEQ ID NO: GALR1fwd 5″ CCCCATCATGTCATCCACCT 3′ 150 GALR1 rev 5′ ATGGGGTTCACCGAGGAGTT 3′151 GALR2 fwd 5′ CATCGTGGCGGTGCTTTT 3′ 152 GALR2 rev5′ AGCGGGAAGCGACCAAAC 3′ 153

The results in Table 30 show that the transfected non-clonal cells andclones have much greater amounts of GALR1 mRNA than the parental cells.In the TVEMP-Galanin cell screening, Clone #7 was shown to be the mostsensitive to TVEMP-galanin. Clone #7 also is shown to have the highestamount of GALR1 mRNA according to Table 30. The CT values for Neuro-2aGalR1 clone 7 (Neuro-2a #7) was the lowest, followed by clone 4 and thenclone 12. The non-clonals tested at this time provided a CT close toclone 12, however, these cells contain a constantly changing populationof cells containing varying concentrations of GalR1 receptor, andtherefore were not considered a good population for future work. Of thethree clones with low EC₅₀'s, Neuro-2a clone GalR1 clone #12 (Neuro-2a#12) grew the fastest, followed by Neuro-2a clone #7 and lastly Neuro-2aclone #4. In addition to its slow growth rate, Neuro-2a clone #4 was nottested further because the sensitivity of Neuro-2a clone #7 was muchbetter than for clone #4.

TABLE 30 Large differences in GALR1 mRNA in Neuro-2a transfected clonalcells vs. transfected non-clonal and parental cells. Cell line ParentalNon-Clonal Clone 4 Clone 7 Clone 12 Ave CT 32.0 21.7 20.8 19.3 21.6 foldmRNA 1.0 1269.5 2418.7 6793.8 1332.6 change5. Comparison of the Sensitivity and Specificity of Neuro-2a Clones #7and #12 with TVEMP-Galanin Compounds

The two clones were tested side-by-side in an attempt to identify themost sensitive and selective of the two, so that data could beconfidently collected from the best performing clone. Table 31 shows theresults of these two clones when treated with TVEMP-galanin Batch C andLH_(N)/A for sensitivity and selectivity respectively. Both clonesexhibit high Signal-to-Noise ratios. Neuro-2a Clone #7 has an EC₅₀ of5.5 nM while the EC₅₀ for Neuro-2a clone #12 is 68.4 nM. The Neuro-2aclone #12 has to be tested with a dose range of 0-300 nM, while theNeuro-2a Clone #7 can be tested with a dose range of 0-30 nM to elicit aplateau at the highest concentration used. Both clones show goodseparation between the LH_(N)/A and TVEMP-galanin Batch C, Neuro-2aClone #12 shows some non-specific uptake at the high concentrations,while Neuro-2a Clone #7 does not. As seen in the tabulated results, therange for testing with Neuro-2a #7 cells is 10-fold lower than that forNeuro-2a #12 cells resulting in a 10-fold less compound being used forNeuro-2a #7 than Neuro-2a #12. Neuro-2a #7 is 8-fold more selective thanNeuro-2a clone #12 when LH_(N)/A was used as a comparison. TheSignal-to-Noise ratio is over 100 for both clones, however a ratio of 10would be sufficient to develop a cell based potency assay. The EC₅₀ forthe Neuro-2a #7 clone is 5.5 nM about 12-fold lower than that forNeuro-2a #12, whose EC₅₀ is 68.4 nM. The lower dose-range for testing,the 24-fold selectivity over LH_(N)/A, the high signal-to-noise ratio,the excellent sensitivity resulting in low EC₅₀, and the low amount ofprotein required for each test, all imply that Neuro-2a Clone #7 wouldbe the clone to go forward with the cell-based potency assay for use indetermining potency ratios for TVEMP-galanin compounds.

TABLE 31 Comparison of characteristics of Neuro-2a clone #7 and #12.Neuro-2a #7 Neuro-2a #12 Range 0-30 nM 0-300 nM Selectivity 24-fold3-fold Signal-to-Noise ratio 190 547 Percent of max LH_(N)/A signal overmax 4.3% 37.6% TVEMP-Gal signal EC₅₀ 5.5 nM 68.4 nM Protein required ~1μg ~10 μg Neuro-2a # 7 and #12 were treated with TVEMP-galanin Batch Cand LH_(N)/A for 16 hours in CM. Activity was detected using ECL-ELISA.

Example XVI Generation of Clonal Cell Lines Overexpressing the KOR-1Receptor for Dynorphin a Retargeted Endopeptidase Uptake

The following example illustrates how to characterize and compareseveral clonal cell lines originated from an established cell linetransfected with the target receptor and subsequent cloning of the cellline. This specific example refers to the identification andcharacterization of clonal cell lines transfected with hKOR-1 that werefirst described in Example III, Table 9.

Four of the AGN P33-KOR clones (clones number 8, 9, 10, and 12 Table 9in Example III) were selected and tested with Dyn/A with a full doseresponse of 0-150 nM. At the same time, two SiMa-KOR clones (clonesnumber 12, and 16 from Table 9 in Example III) selected and tested withwith Dyn/A with a full dose response of 0-150 nM. In this experiment,AGN P33-KOR clones 8, 9, and 12 produced very low uptake and weretherefore discarded; AGN P33-KOR clone 10 displayed good uptake and anEC₅₀ of 30.3 nM was obtained. The two SiMa-KOR clones tested displayedgood uptake and an EC₅₀ of 26.6 nM was obtained for clone 16 and an EC₅₀of 11.8 nM was obtained for clone 12. These three clones were thentested for sensitivity and selectivity by comparing the uptake of thetarget Dyn/A compound against the negative control LH_(N)/A that lacks atargeting ligand and the Noc/A control. The comparison of the threeclones and the parental SiMa cells utilizing a full dose response of0-150 nM is summarized in Table 32.

TABLE 32 EC₅₀ Dyn/A EC₅₀ LHN/A EC₅₀ Noc/A Cell Line (nM) (nM) (nM) SiMaParental >100 >100 5.4 AGN P33-KOR clone 10 9.7 >150 9.4 SiMa-KOR clone16 10.6 >100 1.6 SiMa-KOR clone 12 4.65 >150 19.7

There was a marked increase in Dyn/A uptake in the KOR-1 transfectedclones treated with Dyn/A while the parental SiMa cells showed minimaluptake of the compound (uptake was similar to the negative controlLH_(N)/A). There is some Noc/A in all the cell lines including parentalSiMa cells. This is not surprising as uptake of Noc/A in SiMa cells wasobserved during the assay development for this retargeted compound.Moreover, Noc/A uptake is best in the AGN P33 cell line that wasspecifically derived for this retargeted endopeptidase. The differencebetween Noc/A uptake and Dyn/A compound uptake is greater in the clonalSiMa-KOR clone 12 (SK12) cells. In all the graphs, activity of thenegative control, LHN/A, is minimal, showing that in the absence of thebinding domain there is no specific uptake in these cell lines and thelowest was in the SK12 cells showing that the uptake of the Dyn/Acompound is highly specific. From these results, the SK12 clone wasselected for future optimization and characterization.

Optimization studies were performed with the SK12 cells in order todevelop a robust, specific and sensitive assay. Several parameters wereassayed including plating media and plating densities, treatment media,and treatment time. A summary of the data obtained during theoptimization is provided in Table 33.

TABLE 33 Medium used Treatment Cells/well plating treating time 2500050000 75000 100000 150000 complete complete 6 hr + o/n 51.3 76 13.4 9.2n/a complete complete 16 hr 21.3 19.0 4.96 4.64 n/a complete complete 16hr n/a n/a n/a 2.1 15.3 serum free serum free 16 hr n/a n/a n/a 9.0 12.1complete serum free 16 hr n/a 10.3 5.4 8.97 8.38 complete complete 16 hrn/a 7.7 4.86 13.72 11.26 serum free serum free 16 hr n/a 11.2 8.5 8.49.2

Table B shows that cells plated at 100,000 cells per well in CM andtreated with compounds in CM showed more variability in EC₅₀ values fromone experiment to the next (4.6; 1.2 and 13.72 nM) while cells plated at100,000 cells per well in SFM and treated with compounds diluted in SFMprovided the best curves and consistent EC₅₀ values (9.0 and 8.4 nM). Infuture, cells would be plated at 100,000 cells per well in SFM andtreated with compounds in SFM too.

SK12 plated on PDL plates at 100,000 cells per well in SFM for 24 hours,followed by treatment in SFM for 16 hours yielded the lowest EC₅₀ valueof 8.4+/−1.1 nM and a Signal-to Noise ratio of 12. Both these valueswould be acceptable for future use of this cell in CBPA.

Characterization of SK12 Cells with the Saturation Binding Assay

The saturation Binding assay utilized here was described in detail inExample V. Saturation binding studies were performed using the KOR-1antagonist ³H-diprenorphine to evaluate binding. The total, specific,and non-specific binding were measured in several experiments. Asaturation binding curve of ³H-diprenorphine with the receptor wasgenerated from two independent experiments. It appears that about 25%binding is non-specific and 75% specific binding of the molecule to thereceptor. The affinity of the molecule to the receptor is adequate at6.5 nM. The Bmax indicates that there are 23 fmol KOR-1 receptors percell on the SK12 cells.

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as molecular weight, reaction conditions,and so forth used in the specification and claims are to be understoodas being modified in all instances by the term “about.” Accordingly,unless indicated to the contrary, the numerical parameters set forth inthe specification and attached claims are approximations that may varydepending upon the desired properties sought to be obtained by thepresent invention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques. Notwithstanding that the numerical ranges and parameterssetting forth the broad scope of the invention are approximations, thenumerical values set forth in the specific examples are reported asprecisely as possible. Any numerical value, however, inherently containscertain errors necessarily resulting from the standard deviation foundin their respective testing measurements.

The terms “a,” “an,” “the” and similar referents used in the context ofdescribing the invention (especially in the context of the followingclaims) are to be construed to cover both the singular and the plural,unless otherwise indicated herein or clearly contradicted by context.Recitation of ranges of values herein is merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range. Unless otherwise indicated herein, eachindividual value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein isintended merely to better illuminate the invention and does not pose alimitation on the scope of the invention otherwise claimed. No languagein the specification should be construed as indicating any non-claimedelement essential to the practice of the invention.

Groupings of alternative elements or embodiments of the inventiondisclosed herein are not to be construed as limitations. Each groupmember may be referred to and claimed individually or in any combinationwith other members of the group or other elements found herein. It isanticipated that one or more members of a group may be included in, ordeleted from, a group for reasons of convenience and/or patentability.When any such inclusion or deletion occurs, the specification is deemedto contain the group as modified thus fulfilling the written descriptionof all Markush groups used in the appended claims.

Certain embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention. Ofcourse, variations on these described embodiments will become apparentto those of ordinary skill in the art upon reading the foregoingdescription. The inventor expects skilled artisans to employ suchvariations as appropriate, and the inventors intend for the invention tobe practiced otherwise than specifically described herein. Accordingly,this invention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

Specific embodiments disclosed herein may be further limited in theclaims using consisting of or consisting essentially of language. Whenused in the claims, whether as filed or added per amendment, thetransition term “consisting of” excludes any element, step, oringredient not specified in the claims. The transition term “consistingessentially of” limits the scope of a claim to the specified materialsor steps and those that do not materially affect the basic and novelcharacteristic(s). Embodiments of the invention so claimed areinherently or expressly described and enabled herein.

Furthermore, numerous references have been made to patents and printedpublications throughout this specification. Each of the above-citedreferences and printed publications are individually incorporated hereinby reference in their entirety.

In closing, it is to be understood that the embodiments of the inventiondisclosed herein are illustrative of the principles of the presentinvention. Other modifications that may be employed are within the scopeof the invention. Thus, by way of example, but not of limitation,alternative configurations of the present invention may be utilized inaccordance with the teachings herein. Accordingly, the present inventionis not limited to that precisely as shown and described.

We claim:
 1. A method of detecting the activity of retargeted endopeptidase in a sample, wherein the retargeted endopeptidase comprises an enzymatic domain, the method comprising (a) contacting a cell with a sample suspected of comprising a retargeted endopeptidase, wherein the cell is from an established cell line expressing a SNAP-25 polypeptide consisting essentially of at least a portion of human SNAP-25 comprising SEQ ID NO:5 cleavage by the enzymatic domain, and wherein the established cell line is susceptible to intoxication by the retargeted endopeptidase at about or less than 50 nmol per liter culture medium, as indicated by the enzymatic cleavage of the SNAP-25 polypeptide by the enzymatic domain to yield a fragment of said SNAP-25 polypeptide comprising the amino acid sequence of SEQ ID NO:38; (b) isolating polypeptides from the cell; (c) contacting the polypeptides with an antibody selected from the group consisting of 1 D3B8 having a heavy chain variable region comprising amino acid sequence of SEQ ID NO: 72 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 84, 2E2A6 having a heavy chain variable region comprising amino acid sequence SEQ ID NO: 76 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 88, 3C1A5 having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 78 and a light chain variable region comprising the amino acid sequence SEQ ID NO: 90, and 3C3E2 having a heavy chain variable region comprising amino acid sequence of SEQ ID NO: 80 or SEQ ID NO: 82 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 92; and (d) detecting the presence of the antibody-polypeptide complex, wherein a higher amount of the antibody-polypeptide complex detected correlates to a higher amount of activity of the retargeted endopeptidase in the sample.
 2. The method of claim 1, wherein the antibody is 2E2A6 having a heavy chain variable region comprising amino acid sequence SEQ ID NO: 76 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:
 88. 3. The method of claim 1, wherein the antibody is 3C1A5 having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 78 and a light chain variable region comprising the amino acid sequence SEQ ID NO:
 90. 